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W-ller Of Killers 



Copyright 1946 by 
Industrial Research Service 

Ail rights reserved. This book, or any part thereof, 

may not be reproduced in any form without 

written permission from the publishers. 

Printed in the United States of America 

Composed and Printed by 


Rochester, N. H. 




by O. T. ZIMMERMAN. Ph. D., 
Professor of Chemical Engi- 
neering, University of New 


Formerly Professor of Chem- 
ical Engineering and Head 
of Department, University of 
North Dakota. 







Man Conquers the Louse 1 

The American Army stops a potential epidemic of 
typhus in Naples. 

The Battle of the Centuries 2 

Since man first appeared, he has been fighting a battle 
for survival with his enemies — the insects. 

More Destructive Than Wars 4 

The toll of wars is tremendous, but it is small com- 
pared to the destruaion of human lives by insects. 

The Black Death 5 

Bubonic plague — the scourge of mankind. 

Rats, Fleas, and Plague 7 

The role of rats and fleas in transmitting bubonic 

Lice, Fever, and Death 10 

Typhus, follower of armies throughout the centuries. 

Mosquitoes and Quinine 15 

Malaria — disease of chills and fevers — and the life- 
giving bark. 

Yellow Jack 21 

The successful battle against yellow fever. 

Animals, Insects, and Man 25 

Animal reservoirs of disease, and the role of insects 
in transmitting disease to man. 


Unwept, Unhonored, and Unsung 30 

Othmar Zleidler, a German chemist, prepared DDT in 
1874 but failed to recognize its properties. 

The Lost is Found 32 

DDT is rediscovered by the Geigy Company of Swit- 



vi Contents 

What Is DDT? 39 

A brief discussion of the properties and preparation 
of the insecticide. 

Free Enterprise 42 

Civilians get DDT when a young, enterprising chem- 
ist forces the hand of W.P.B. 


Did It Taste Good.? 44 

A human guinea pig — a farm hand — chews DDT with 
his tobacco. 

Don't Be Afraid! 45 

Words of caution were misinterpreted to mean danger 
when DDT first came onto the market. 

How Much is Fatal? 47 

Tests on dogs, cats, and other animals show that large 
doses of DDT can be tolerated. 

Will DDT Poison Warm-Blooded Animals? 49 

DDT is toxic to animals if taken in large quantities, 
but it takes a lot to harm warm-blooded animals. 

Do You Inhale? 51 

The inhalation of DDT sprays is not apt to cause 

Your Lily-white Skin 52 

DDT in solvents can be absorbed by the skin, but the 
danger to humans has been greatly exaggerated. 

DDT Crashes the Barrier 54 

A further discussion of the effects of DDT solution 
on the skin. 

The Poor Fish 60 

DDT is much more toxic to cold-blooded animals than 
it is to mammals. 

It's a Bird! 61 

Birds can tolerate about the same proportional quan- 
tities of DDT as can warm-blooded animals. 

The Killer of Killers at Work 62 

DDT acts as both a stomach poison and a contact 

DDT Jitters , 64 

DDT attacks the nerves. 

Contents vii 


From Laboratory to You 67 

An outline of the various types of DDT formulations. 

Sprays and Sprays 69 

The difference between space sprays and residual sprays 
is discussed. 

Grade AA 71 

The significance of the different grades of space sprays. 

100% Active 74 

The solvents used in sprays contribute to the killing 

Oil to You 74 

Kerosene, the common DDT solvent. 

Why DDT in Space Sprays? 79 

A small percentage of DDT in space sprays greatly 
increases the kill. 

The Killing Mist 80 

The aerosol bomb and how it works. 

Long-Lived Action 82 

The residual spray for long-lasting action. 

Powdered Death 84 

DDT powders for the control of lice, fleas, ants, and 

Milky White 85 

DDT emulsions and their advantages. 

Powders That Wet 87 

Dispersible powders for use in barns and on livestock 
and crops. 

Dust the Plants 88 

DDT powders for agricultural purposes. 

Save the Surface 89 

DDT in paints. 


The Lousy Louse 91 

Types of lice and how they live. 

What's That In Your Hair? 93 

The head-louse and how it can be controlled. 

yiii Contents 

Right Where It Hurts 100 

The crab or pubic louse succumbs to DDT. 

Your Bedtime Companions 101 

Bedbugs are eflFectively controlled by DDT. 

The Ubiquitous Fly 103 

The housefly spreads disease. 

Flies and Polio 104 

The probable influence of the fly in the spread of 

The Fly and the Horse 106 

Where there are horses there are flies, since flies breed 
on manure. 

An Island Paradise 108 

Mackinac Island keeps the horse, but gets rid of the 


Contented Cows 109 

DDT used in dairy barns and on catde reduces the 
fly population and results in an increased yield of 

The Female of the Species 112 

The deadly mosquito and how it can be controlled. 

Ants in Your Pantries 120 

How to rid your home of ants. 
The Wood Eaters 122 

How termites can be controlled with DDT. 

A Dog's Life 124 

Fido's life is made more happy by DDT. 
Tick, Tick 126 

The control of ticks. 
Down on the Farm 128 

The use of DDT against agricultural pests. 
Beauty and the Beasties 130 

Butterflies and moths. 
Homes in the Raw 133 

Insect enemies of forest trees. 


The Balance of Nature 137 

The fear that DDT will destroy the balance of na- 
ture is unjustified. 

Contents ix 

The Busy Bee 139 

The use of DDT in agriculture will not destroy the 
bee world. 

Tougher Bugs 142 

The use of insecticides and medicinal agents results 
in more resistant species of inserts and bacteria. 


What Next? 144 

DDT is a marvelous insecticide, but tougher species 
of insects will probably evolve and still newer insect 
killers will have to be developed if we are to prevent 
insects from inheriting the earth. 


Part I 149 

Instructions for the use of DDT in the control of the 
common insert pests that affert man and animals. 

PART II 163 

Instrurtions for the use of DDT on vegetables, fruits, 
flowers, and shade and forest trees. 

INDEX 171 


1. Dr. Paul Miiller, whose experiments led to the discovery of 

the magic insect killer — ^DDT 17 

2. Dead flies are removed from a small test box which had 
been sprayed 15 minutes previously with a DDT-kerosene 
solution 18 

3. Youngsters are treated with DDT powder during the Army 
Medical Service's successful campaign to stop the typhus 
epidemic in Naples in early 1944 35 

4. Captain Arthur W. Hill, of Washington, D. C, and T/5 
Joseph Russotto, of Bayonne, New Jersey, apply louse-killing 
DDT powder to an Arab family at L'Arba in Algeria .... 36 

5. CxAonel W. S. Stone dusts an Arab with DDT louse powder 37 

6. This soldier won't be bothered by lice after his dusting with 
DDT powder 38 

7. An unsung hero of the War — ^A volunteer lets body lice feed 
on his back in experiments that helped government agencies 
develop DDT for use against the typhus-carrying louse. The 
lice, on patches of cloth, are allowed to feed on the subject's 
back and are then removed 55 

8. There won't be any flies in this room after the young lady 
finishes spraying 56 

9. A wise housewife knows that insects like to hide in dark 
places • . . . 57 

10. There will be no fleas in this house after the floors and rugs 

are sprayed with a 5% DDT-kerosene solution 58 

1 1. Garbage cans sprayed inside and outside with 5% DDT will 

not be breeding grounds for flies 75 

12. A flick of the valve and the death-dealing DDT mist from 
this aerosol bomb will spell the doom of every insect flying 

or hiding in this room 76 

13. Sergeant Edward J. Haladay releases an aerosol mist to kill 
any insects that are lurking in the barracks where his com- 
pany sleeps 77 


List of Illustrations xi 

14. Nurse Willis Craft sprays a bed at the Arlington, Va. County 
Hospital with 5% DDT to eliminate the bedbug problem . 78 

15. This soldier is treating the interior surfaces of a barrack 
with DDT residual spray to insure immunity against mos- 
quitoes for several weeks 95 

16. A measured quantity of a household spray is atomized into 
a Peet-Grady chamber in order to determine the effective- 
ness of the insecticide 96 

17. Flies knocked down during a Peet-Grady test are picked up 
and counted. They are then transferred to a cage to see 

how many recover within 24 hours 97 

18. This Piper Cub airplane is spraying a DDT formulation over 
mosquito-infested terrain. This treatment kills mosquitoes 

and larvae as well as adult stages of their life cycle 98 

19. To kill mosquitoe larvae in flowing water, a drip can feed- 
ing a DDT in oil solution is very convenient 115 

20. A rotary-type hand duster being used to treat a mosquito- 
breeding place with DDT 116 

21. These Walker-Gordon cows will be more contented after 

the dairy is sprayed with a water suspension of DDT 117 

22. Cows kept free from flies by direct application of DDT will 

give from 3 to 8% more milk than their untreated sisters . 118 

23. This pig will remain free from flies and lice for a long time 
after her treatment with a 5% DDT dispersion in water . . 135 

24. Cattle on a Florida ranch are sprayed with DDT for control 

of the horn fly 136 

Chapter One 

Man's Mortal Enemies 

Man Conquers The Louse 

1 HE AMERICAN ARMY was in action. 
It had recently established its beachhead at Salerno and was 
now fighting its way up the Italian peninsula. Then signs 
of disaster appeared! It was not a reinforced German Army 
or an Italian Army suddenly inspired to put up a fight. No, 
it was the lowly louse or, more specifically, millions or bil- 
lions of lowly lice. 

In all the previous wars of history, the louse had killed 
more men that had ever died from bullets, swords, or other 
weapons. Would this war be a repetition of the history of 
the past? Would lice stop the advancing American Army 
and kill thousands of our fighting men? Things looked 
black! Over a million poverty-stricken people were crowded 
into the city of Naples — a population without fuel, water, 
or light; a terror-stricken population crowded together in air- 
raid shelters; a population covered with lice. And lice carry 
that dreaded disease — typhus. 

It was the month of October in the year 1943; and that 
month the hospitals of Naples received 25 typhus cases. To 
all who know that dreaded disease, this was an ominous sign, 
for throughout all the years of history whenever typhus had 
broken out at the beginning of winter, it had never been 

2 DDT — ^Killer of Killers 

brought under control until the warmer weather of March 
or April had arrived. When typhus cases increased to 40 a 
day in December and to 60 a day in January, and people 
were dying in the gutters of Naples, it was evident to all that 
a full-scale epidemic had arrived, and that by February — un- 
less something drastic could be done — 500 people a day 
would be coming down with this disease of unclean liness. 

The American soldiers had been vaccinated against 
typhus, but it was impossible to vaccinate the entire popula- 
tion of Naples. Realizing the seriousness of the situation, 
Brigadier General Leon Fox, Field Director of the American 
Typhus Commission in Cairo, flew to Naples to see what he 
could do. General Fox knew about the magic new wonder 
killer DDT and how it had protected our troops against lice 
during the invasion of Africa. He decided to use it in an 
experiment of tremendous magnitude. In the month of 
January alone, 1,300,000 people in Naples were dusted with 
DDT powder, and as more refugees entered the city they 
were immediately given this treatment. The typhus epidem- 
ic passed as rapidly as it had started — by the middle of Feb- 
ruary it was completely under control. This was the first 
time on record that a typhus epidemic had been stopped in 
mid-winter; and for the first time in history that scourge of 
war — typhus — had been licked. 

The Baf-fle of the Centuries 

Man, throughout the countless centuries since he first 
appeared on earth, has gradually managed to fight his way 
to the top of the animal kingdom. The giant mammoth 
and dinosaur exist only as skeletons in museums; the tiger 

Man's Mortal Enemies 3 

and the lion hide in the deep jungle or the bushy veldt, away 
from the powerful firearms that man's ingenious brain has 
devised to make up for his lack of physical strength. But 
the outcome of that age-long battle between mankind and 
the insea world is still uncertain. 

At times the insect hordes get the upper hand, and mil- 
lions of human beings drop dead from the poison injected 
into their bodies by mosquitoes, lice, fleas, or ticks, while 
others die through eating food poisoned by the ubiquitous 
fly as he makes his daily round from the manure pile, the 
privy, or the garbage can to the kitchen table. But even 
these deaths, horrible as they may be, are no worse than the 
millions of other deaths due to famine, caused all too often 
by the incessant appetite of inseas for the same food that 
man consumes. According to Dr. P. N. Annand of the U. S. 
Department of Agriculture, destruction of crops by agricul- 
tural inseas costs United States farmers two billion dollars 
a year, or as Dr. L. O. Howard puts it, devastation by insects 
undoes the work of a million men. 

At other times, man gains a significant victory over his 
enemies. He concocts a vaccine to neutralize the effect of an 
insect's bite; he destroys the breeding grounds of his assail- 
ants; or he develops a poison that wipes out the insects faster 
than they can breed. But the latter is a difficult task, for 
birth control is certainly not praaiced by our tiny foes. New- 
born insect children can look forward to becoming parents 
in a few days or even a few hours; and, although human quin- 
tuplets make the headlines throughout the world, an insect 
mother who produced only five offspring at a time would 
hang her head in shame at this evidence of her virtual steril- 

4 DDT — Killer of Killers 

More Desf-rucfive Than Wars 

In World War II — ^the most recent of the many con- 
flicts in which man has killed his fellow man — the toll of 
human life was staggering. The American forces alone 
counted almost 400,000 dead, including those who died from 
natural causes and behind-the-lines injuries. Among the 
Russian and German Armies, the dead must have numbered 
in the millions; and additional millions were added to the 
list by the other belligerent nations. This is the penalty we 
paid for not learning how to get along with each other; but 
it is only part of the penalty, for no one can estimate the sum 
total of human suffering that this one war brought about — 
the agonies of the wounded, the loss of homes and means of 
livelihood, the starvation and disease, the bereavement of the 
survivors, and the hopeless outlook for the future. These are 
the penalties that men have paid throughout the ages for 
their periodic wars against members of their own species. 

We should not attempt to minimize the tragedy of war, 
for wars are senseless and useless, but from an impersonal 
point of view we must admit, for the sake of accuracy, that 
insects have killed many more men and have caused much 
more human suffering than have all the wars of history. And 
in addition, mosquitoes, lice, and fleas have decided the out- 
come of most of men's wars, and have thus played a bigger 
role in shaping the political history of the world than have 
all our military men and statesmen. In fact. World War II 
— thanks to the medical services and DDT — was the only 
major war of history in which diseases transmitted by insects 
did not play a decisive role. 

Man's Mortal Enemies 5 

The Black Death 

Diseases — hundreds of them — are always with us. But 
most of the time they attack only a small proportion of the 
population at a time. But not always! Every once in a 
while the pages of history have been blackened by pesti- 
lences that have spread throughout whole populations, at- 
tacking almost everyone and killing high percentages of those 
so afflicted. And of the many pestilences that have left their 
trail of dead and dying and human suffering, none has struck 
more terror into the hearts of men than has that dreaded 
disease, bubonic plague — the most terrible epidemic of which 
was the infamous Black Death of the l4th century. The 
Black Death, however, was not the only serious epidemic, for 
there had been a number of outbreaks of plague before the 
l4th century, and there have been a number since. 

In the 6th century, during the reign of Justinian I, the 
last of the Roman Emperors, plague came out of the Orient 
and struck Constantinople in the year 532. It soon spread 
to Italy and the rest of Europe, and killed half the population 
of the Roman Empire. Shortly thereafter the Roman Em- 
pire collapsed, and its collapse was due, at least in part, to the 
widespread changes brought about by the ravages of the 

But for widespread destruction, the epidemic known as 
the Black Death is in a class by itself. Introduced into Con- 
stantinople from Asia in the spring of 1347, it quickly spread 
through Greece and the Mediterranean Islands, reached Sicily 
in October, passed on to Naples, Genoa, and Marseilles — 
where four-fifths of the population are reported to have died 
— and reached Dalmatia before the end of the year. It was 
well established in southern France, Italy, and Spain early in 
1 348, reached Paris by June, and was in England and Ireland 

6 DDT — Killer of Killers 

by the fall of the year. Shortly thereafter Germany and the 
Netherlands felt the attack, and by the year 1350 this pesti- 
lence had spread throughout all of Europe, even to the dis- 
tant islands of Iceland and Greenland. 

When the cold, clammy fingers of the Black Death 
touched a community, few inhabitants escaped. In many 
towns and cities, more than half the population died. The 
total number of deaths throughout Europe is hard to believe. 
At last 25,000,000 people — one-fourth of the population of 
Europe — were killed by this visitation of the plague, and 
some authorities place the total deaths as high as three-fourths 
of the whole population. 

But even this destruction of human life did not satisfy 
the demon of the plague, for it returned again and again to 
many parts of Europe over the next thirty years. In many 
regions, one-third of the population was wiped out in 1359 
and 1360; and many Polish towns lost one-half of their popu- 
lations in 1360 and 1361. Ten years later, in 1370, Russia 
was revisited by a severe wave of plague that killed 80,000 
people in Lubeck alone. 

During the next two or three centuries, plague epidem- 
ics broke out every once in a while, and although they were 
not as severe as the Black Death itself, they would all be 
classified as major calamities if they were to occur in 20th 
century America. For example, it has been estimated that 
in Paris alone bubonic plague killed 50,000 in 1418, 40,000 
in 1450, and another 40,000 in 1467. Other cities fared 
just as badly: there were 16,000 plague deaths in Florence in 
1418; 40,000 in Constance in 1438; 30,000 in Venice in 
1477 and 1478, and 18,000 in Vienna; while in Brussels, in 
1502, as many as 500 a day lost their lives. 

Except for minor, localized epidemics, plague was rela- 

Man's Mortal Enemies 7 

tively unknown from the 1 6th century to the year 1871, 
when it broke out in the Chinese province of Yunan-Fu and 
soon spread to surrounding areas. By 1894, when it reached 
Hong Kong, it was a serious epidemic, and when it arrived in 
India it killed six million inhabitants of that country in a 
period of ten years. 

From India the plague spread to the sea ports of all the 
continents of the world, and the United States had its first 
taste of this disease in 1900 when it reached San Francisco. 
The United States' epidemic of plague spread fear through- 
out a population that was well aware of what had happened in 
other parts of the world when plague became established; 
but the worst fears were not justified. The total number of 
recorded deaths was only 314, most of which were reported 
from California although eight other states contributed to the 
total. Undoubtedly, the number of unreported plague deaths 
was much greater than the number reported, but even if we 
allow for these, this epidemic was a far cry from the Black 
Death of l4th century Europe. Nevertheless, everyone 
breathed a sigh of relief when, in 1904, there were indica- 
tions that this outbreak of plague had died out. 

Unfortunately, the United States did not get off as easily 
as it seemed at the time. Plague is here to stay; and some 
day, if we are not careful, the black, distorted features of vic- 
tims of bubonic plague may become commonplace in the 
cities of America. We will explain this a little more fully 
later, but first we should tell you how this disease is spread. 

Rats, Fleas, and Plague 

Throughout the centuries that plague ravaged the earth, 
all efforts to control the spread of the disease were ineffective 

8 DDT — Killer of Killers 

because no one knew its cause or how it was spread. People 
a few hundred years ago were not appreciably different from 
folks today, and they reacted to the unknown in praaically 
the same manner. Some accepted the plague as punishment 
from an angry God and turned to religion for their salva- 
tion. Others felt that there was no hope and threw them- 
selves into all forms of dissipation in attempts to squeeze the 
maximum amount of pleasure from their few remaining days. 
And, as further evidence that the world hasn't changed much, 
some blamed the plague on the Jews, and thousands of un- 
fortunate members of this race, particularly in southern Ger- 
many, were burned to death in their homes. This l4th cen- 
tury persecution — like persecution of the Jews today — often 
had its practical aspeas. Many noblemen owed money to 
the Jews and used the plague as an excuse for eliminating 
their creditors. However, the mass of people knew in some 
vague way that the disease could be transmitted only by some 
physical means; and those who could afford it fled from the 
towns and cities at the approach of an epidemic and avoided 
as much as possible contact with the sick and dying. Very 
often, even flight and quarantine were ineffective: castle 
walls could not keep out the Black Death. 

It had often been observed, even in ancient days, that 
large numbers of rats died during epidemics of human plague. 
But the role of the rat in the transmission of plague was not 
discovered until the present century. The disease itself is 
caused by a specific bacillus, first discovered in 1894 during 
the plague epidemic in Hong Kong. It was later demon- 
strated that plague is primarily a disease of rodents, particu- 
larly rats; and in 1906 the British Indian Plague Commission 
proved that the bacillus is transmitted from rats to man by 
the bite of the flea. 

Man's Mortal Enemies 9 

Actually there are two forms of the disease: the true 
bubonic plague, which one gets when he is bitten by a plague- 
carrying insect; and the pneumonic plague, in which the 
bacillus is carried directly from one person to another by 
means of infected droplets. But, since the pneumonic form 
is merely an outgrowth of the bubonic form of the disease, 
as long as there are rats to act as a reservoir for plague and as 
long as there are fleas to carry the plague to man, the pos- 
sibility of tragic epidemics will always be with us. 

It is probable that most epidemics of human plague 
started when fleas from plague-infested wild rats transferred 
their place of abode to house rats, and the fleas from the 
house rats, upon the death of their hosts, jumped over to 
people. Yet, there is evidence that the rat flea is not the 
only culprit. Cat and dog fleas, fleas on wild and domesti- 
cated birds, and even bedbugs and lice may, under some con- 
ditions, play a part in the spread of the disease. 

And that brings us back to the San Francisco epidemic 
of 1900. This epidemic, as was mentioned before, had run its 
course by 1904, at least as far as anyone then knew. But 
only on the surface. Among the hordes of rats it was still 
smoldering, and worse yet, it had spread from the rats to 
other rodents — ground squirrels, rabbits, chipmunks, prairie 
dogs, etc. — as was discovered in 1906. Since then, plague 
has been found in wild rodents in all of the western states, 
and in many parts of the east. So far, only a few cases a 
year of human plague have been reported, and in all cases the 
viaims were campers, hunters, and children who came in 
contact with the wild rodents. But now that the war is over 
and more and more people are vacationing in the wide-open 
spaces, will the number of plague cases increase? Or will 
fleas from the infected wild rodents carry the disease to our 

10 DDT— Killer of Killers 

city rats and then to the human population? Will plague 
sweep this country as it did Europe in the 14th century? 
We don't know the answers yet. But if the worst does 
come, we will have only ourselves to blame. Unlike the 
inhabitants of medieval Europe, we know how plague is 
spread. We can't pass it off as an act of God. We know 
that we must beware of the flea. He's an ugly looking beast, 
and his bite is worse than his appearance. 

Lice, Fever, and Death 

Next to bubonic plague, the most dreaded of European 
pestilences is typhus, also known as ship fever, camp fever, 
jail fever, and spotted fever. Traditionally, this is the disease 
that for centuries has followed in the wake of armies. World 
War II was no exception, but thanks to DDT, vaccines, and 
the greater cleanliness of modern armies, typhus for the first 
time in history was brought under control. 

As was the case with bubonic plague, hundreds of years 
elapsed before man found out how typhus was spread. It 
was not until 1909, when Charles Nicolle discovered that 
typhus is transmitted from man to man by lice, that the mys- 
tery was stripped from this disease and men learned that 
there was more to body cleanliness than merely the elimina- 
tion of body odor. People who change to clean clothing 
once a week won't harbor body lice, and if these individuals 
take a bath before putting on their fresh garments, so much 
the better. But only a small percentage of the world's pop- 
ulation can boast of a standard of living so high that it per- 
mits of a change of garments and a bath tub. When people 
are crowded together in concentration camps or in city slums, 
when homeless, underfed refugees drag their weary bodies 

Man's Mortal Enemies 11 

through the rubble of bombed-out cities, lice move in to feed 
on the anemic blood of the unhappy individuals. 

Since typhus is transmitted by lice, it is easy to under- 
stand why waves of typhus have devastated Europe and Asia 
for hundreds of years. The first bath tub was introduced in 
to America in about 1840, and for years thereafter many 
prominent medical men of the day wrote learned tracts and 
made impassioned speeches about the dangers of bathing. 
The Saturday-night bath did not become an American tradi- 
tion until many years later, and even then many reactionaries 
continued to resist this revolutionary idea. Imagine what 
conditions must have been like in Europe in, say, the 15 th, 
l6th, or 17th century? Praaically no one bathed, and 
everyone, from the poorest peasant in his filthy rags to the 
proudest queen with her equally filthy petticoats, was infested 
with crawling, biting vermin. 

Typhus is one of the numerous fever-producing diseases 
caused by germs that are intermediate in size between the 
bacteria and the filterable viruses. This class of organisms 
is called the Rickettsiae, after their discoverer, Howard Tay- 
lor Ricketts, an American who, ironically, contracted typhus 
and died in 1910 in Mexico City while he was studying 
tabardillo, the Mexican form of the disease. 

Because the symptoms of typhus are similar to those of 
a number of related diseases, it is impossible for the medical 
historian to estimate when typhus first began to change the 
history of the world. Many of the epidemics described by 
early writers might have been typhus, but the evidence is too 
incomplete for a proper diagnosis. We do know, however, 
that typhus broke out among the army of Ferdinand and Isa- 
bella during the siege of Granada in 1489-1490, and that 
17,000 soldiers are supposed to have lost their lives from 

12 DDT — Killer of Killers 

the disease — ^many more than were killed by the weapons 
of the Moors. 

And in 1528, typhus decided the fate of Europe by en- 
tering into the battle between Charles V and Francis I for 
control of Italy. In 1527, the Imperial Army of Charles V 
marched through Italy, sacked Rome, and made a prisoner of 
the Pope, Clement VII, who was allied with Francis I of 
France. Then plague broke out in the city and killed a large 
proportion of the population as well as the soldiers of the 
Imperial Army. Even the Imperial General, Lannoy, died 
of the disease. The army of Francis I was not long in com- 
ing, and the decimated Imperial troops were in no condition 
to put up a fight. The remnants of the once-proud Imperial 
army managed to get to Naples where they fortified the city, 
and here they were besieged by the French Army under 
Lautrec. The surrounded army was dying of starvation and 
was ready to giwe up when typhus suddenly struck the French 
army of 25,000 men and reduced it within 30 days to about 
4,000 survivors, at least according to some accounts. Lautrec 
was forced to retreat, Clement VII and Charles V patched up 
their differences, and, in 1530, Charles V was crowned ruler 
of the German Empire. 

And yet, to show the impartiality of typhus, Charles V 
was forced to abandon the siege of Metz in 1552, when his 
armies were stricken with a typhus epidemic and 30,000 men 
died from disease. 

A number of other outbreaks of typhus occurred during 
the remaining years of the l6th century, usually when armies 
were on the march — and then came the Thirty Years' War, 
from 1618 to 1648. Few periods of history held so much 
suffering for so many people. It was not the battle casualties 
alone, or even the atrocities perpetrated upon helpless civilian 

Man's Mortal Enemies 13 

populations by conquering soldiers — and these defy all de- 
scription. It was pestilences of all types, and in particular, 
plague and typhus, marching side by side with the armies, 
that accounted for the majority of the deaths and decided the 
outcome of many of the battles. The 60,000 deaths in Ly- 
ons and the 25,000 in Limoges in 1628 are merely examples 
of what took place all over Europe. 

Skipping the pages of history to another decisive war^ 
the campaign of Napoleon against Russia in 1812, we again 
find the louse of greater importance than the generals. Every- 
one has read of the dreadful suffering of Napoleon's troops 
when they retreated from Moscow — how men froze to death 
by the thousands and died of starvation. Of an army of over 
half a million men at the beginning of the campaign. Napo- 
leon returned to Paris with only a handful. About 300,000 
men perished from disease alone — about twice as many as 
died from battle wounds — and of these typhus accounted for 
a large proportion, although dysentery and pneumonia killed 
no small number. 

When most of us think of the Crimean War, that took 
place in 1854-1856, we think of either Florence Nightingale 
or the "Charge of the Light Brigade." But instead of shed- 
ding too many tears over the "noble 600," let's pay our re- 
spects to the more than 100,000 who died from disease. It 
is impossible to say how many of these deaths were due to 
typhus and how many to cholera and dysentery, but reliable 
accounts inform us that there were two violent typhus epi- 
demics during the war, and that they struck the opposing 
armies with about equal intensity. 

In World War I, there were also two severe typhus epi- 
demics, and future historians may record the fact that both 
played important parts in shaping the history of the world 

14 DDT— Killer of Killers 

from the year 1914 on. The first outbreak occurred in 
Serbia in November of 1914. It started among the Austrian 
prisoners whom the Serbians had captured, and soon spread 
throughout the Serbian Army and the civiHan population. 
In less than six months over 150,000 people had died, and 
Serbia was practically helpless. The Austrian Army could 
easily have gone through Serbia and attacked Turkey, Bul- 
garia, and Greece before these countries could have put up an 
eifeaive resistance. But fear of typhus held them back, and 
the Central Powers lost their initial advantage. 

Typhus flourished among the Eastern armies through- 
out the war, but vigorous delousing programs kept it pretty 
well under control among the Germans and Austrians. How- 
ever, after the retreat of the Russian armies in 1916, typhus 
cases in Russia began to increase in number, and a full-scale 
epidemic, like those that had devastated Europe in the Middle 
Ages, was on its way. The spread of the disease was ac- 
celerated by the chaotic conditions of civil war; and between 
the years 1917 and 1921 there were 25,000,000 victims of 
typhus in the Soviet Republic, and from 2% to 3 million of 
the viaims died. 

Because World War II passed without a major typhus 
epidemic, we might be inclined to assume an attitude of com- 
placency and delude ourselves into believing that "it can't 
happen here!" That would be unfortunate, for there are 
dark clouds on the horizon. Typhus is not unknown in this 
country. Although there have been no epidemics of the 
classical European type, there have been occasional localized 
outbreaks of the disease. Since the typhus-infected louse can 
live for not over 12 days, it seemed highly improbable to 
students of typhus that these sporadic attacks were due to 
transmission of the disease from man to man by lice. They 

Man's Mortal Enemies 15 

decided to investigate; and their investigations showed that 
typhus can be carried by household rats — and probably by 
other rodents — and that it is transmitted from rat to rat by 
rat fleas and rat lice. Of course, when a flea carrying the 
deadly Rickettsiae bites a human, the disease can become es- 
tablished in man, and if the victim is lousy, he can in turn 
pass the disease on to those with whom he comes in contaa. 
Thus, the rat is not only the carrier of plague — he is also a 
reservoir of typhus. And keeping our bodies free from lice 
is not sufficient assurance that we will not get typhus. We 
must also look out for the flea. 

Mosquif-oes and Quinine 

Many Americans who fought the war in the Pacific 
brought back to their native land millions of unwanted sou- 
venirs: tiny protozoa in their red blood cells. These organ- 
isms, the germs of that debilitating disease, malaria, were in- 
troduced into the bodies of our soldiers by female members 
of a class of mosquitoes known as Anopheles. However, it 
is not necessary for a resident of this country to leave the 
borders of the U. S. A. in order to gQt malaria — the disease is 
well established in at least 36 of our states and it has been 
known to exist in most of the others. Although Laveran 
discovered the protozoa of malaria as early as 1880 and 
Ronald Ross discovered the role of the mosquito in the trans- 
mission of the disease in 1895, we have accomplished little 
in the way of mosquito control, and are still relying on quinine 
or newer drugs such as atebrin to make life tolerable in re- 
gions where Anopheles reign. 

Malaria is not a disease, like bubonic plague or typhus, 
that kills a high percentage of those that it attacks, but it 

16 DDT — Killer of Killers 

saps the strength of its victims and makes them miserable for 
a long, long time. Yet, even though malaria does not kill 
most of its victims, so many people throughout the world 
contract this lingering disease each year that the small per- 
centage who die from it comprise a by-no-means insignificant 
total. Reliable figures are impossible to obtain, but avail- 
able evidence indicates that at least 3,000,000 of the world's 
inhabitants die from malaria each year, and probably a hun- 
dred times that number are made ill. How many malaria 
viaims die not from the disease itself but from other infec- 
tions which gain a foothold in their malaria-weakened bodies 
is anybody's guess, but the total must be at least as great as 
the number killed directly by the disease. 

That malaria has played an important part in the his- 
tory of the world is beyond question. After the campaign of 
the Greeks against the Egyptians in 456 B.C., the soldiers of 
Hannibal brought back malaria, and ever since, the Mediter- 
ranean basin has been a favorite breeding ground for germ- 
carrying mosquitoes, waiting to pass on the disease to those 
who dare enter their domain. The mosquitoes lost no time 
in spreading malaria among the Greeks in those long-passed 
days. Before long, the population was so weakened by 
germs in their blood cells that Greek civilization was on the 
down grade, and the Greeks were in no condition to with- 
stand the arms of the Roman legions. 

The movement of armies has always been a big factor 
in the spread of malaria, as the Crusaders, the troops of Napo- 
leon, and the British Tommies all found out. In our own 
Civil War, over 50 percent of the white troops and over 
80 percent of the negro troops fell victims to malaria each 
year; and our Spanish-American soldiers found malaria a 
more formidable enemy than the Spaniards. Incidentally, 

Fig. 1. Dr. Paul Muller, Whose Experiments Led to the 
Discovery of the Magic Insect Killer — DDT. 

(Courtesy of Geigy Company, Inc.) 


Fig. 2. Dead Flies are Removed from a Small Test Box 

Which Had Been Sprayed 15 Minutes Previously with 

A DDT-Kerosene Solution, 

(Courtesy of U. S. Dept. of Agriculture) 


Man's Mortal Enemies 19 

when the malaria-infeaed troops returned from the latter 
war, our native mosquitoes took advantage of the opportunity 
to spread malaria among the civilian population. And it is 
highly probable that malaria victims among the veterans of 
World War II have been the unwitting sources of recent 
localized malaria epidemics in the United States. 

The name malaria is derived from two words: mal, 
meaning bad, and air. Thus the literal meaning of the word 
is bad air. Long before the role of the mosquito in the 
transmission of the disease had been discovered, men knew 
that in some way the air in the vicinity of swamps and other 
wet places was dangerous. They believed, of course, that 
evil spirits emanated from the swamps and entered their 
bodies, causing the chills and fevers, and weakness. This 
theory was almost correct. But unfortunately, no one real- 
ized that the evil spirits had wings and a death-dealing bite. 
Yet the idea of a relationship between swamps and malaria 
was quite correct, for water \s essential for the breeding of 
mosquitoes — during the larval stage they are aquatic insects. 

Since mosquitoes require water, we would except to find 
malaria along the shores of the oceans, in river valleys, 
around lakes and swamps, and in damp jungles — that is, un- 
less the winters are too cold to permit mosquitoes to survive. 
Inhabitants of Asia — particularly of China and India — Mex- 
ico, Central America, South America, and the southeastern 
part of the United States have all had to learn to live with 
malaria. The use of screens on windows, the draining of 
swamps, the application of oil and insecticides to breeding 
places of mosquitoes have helped in some localities, but all 
of these efforts have been insignificant compared to the bene- 
fits conferred by a medicinal agent — quinine — extracted 
from the bark of the cinchona tree. 

20 DDT— Killer of Killers 

Whether cinchona bark was first used by the South 
American Indians or whether the Jesuits deserve credit for 
discovering its magical properties is of no importance. But 
since about the year 1630, the bark itself, or quinine, the ac- 
tive principal extracted from the bark, has alleviated the 
sufferings of untold millions. Today, when armies move 
into malaria-ridden districts, everyone is given his daily dose 
of quinine or the synthetic atebrin, and we all thrill to stories 
of jungle explorers calmly taking quinine pills while fighting 
wild animals and poisonous snakes. Quinine is not the per- 
fect answer to malaria control. In fact, it is probably in- 
correct to say that quinine "cures" the disease. If one takes 
quinine regularly before he enters a malaria-infested district, 
and if he keeps up the treatment while he is there, the chances 
are that he will not get the disease — but he can't be sure, for 
some individuals become infeaed in spite of quinine pro- 
phylaxis. After one has contracted malaria, quinine treat- 
ment will lessen the severity of the disease, but it will not 
eradicate it. 

The story of quinine is very much like that of rubber. 
For over two hundred years after cinchona bark was first used 
in the treatment of malaria, the world had to depend entirely 
for its supply on the wild trees of South America. Then the 
situation changed. Sir Clements Markham went to South 
America with an expedition in I860 and procured over 400 
cinchona plants and a number of seeds, with which he started 
plantations in India. And two years later a Dutch expedi- 
tion under a botanist by the name of Hasskarl managed to 
get out of South America with about 500 cinchona plants 
and a number of seeds. Two plants survived the journey to 
Java where they were planted, along with the seeds, to start 
the cinchona industry in the Netherlands Indies. 

Man's Mortal Enemies 21 

The yield of quinine from the original plantings was 
very low, but in 1865 seeds of a high-yield variety were 
brought from South America by Charles Ledger, who turned 
them over to the Dutch when the British Government re- 
fused to accept them. With these seeds, the cinchona indus- 
try was established in Java on a large scale, and that country 
was supplying 95 percent of the world's quinine require- 
ments when the Japs moved in, in 1942. The reason for 
the quinine shortage during World War II is, therefore, ob- 

Although malaria has been with the world for a few 
thousand years, it is more of a problem today than ever be- 
fore. With airplanes covering thousands of miles in a com- 
paratively few hours, malaria can easily spread to regions 
where it was formerly unknown. Infected mosquitoes can 
ride the airways and live to start an epidemic half way around 
the world from where they were born. Or, a person may 
pick up the infection in one country and not become sick un- 
til he is back home. All we can do is try to keep the mos- 
quitoes under control. We can't hope to kill all the mos- 
quitoes over millions of square miles of jungles, but we 
should do our best to keep down their numbers around our 
cities and towns. 

Yellow Jack 

In June, 1946, our newspapers carried notices of the 
death of a 68 -year-old man. Ordinarily there is nothing un- 
usual about this, for every time a prominent businessman, 
politician, or gangster dies, the newspapers dig into their 
morgues and do their best to find a few kind words to say 
about the deceased — and this is often a difficult task. But 

22 DDT— Killer of Killers 

this man, whose passing did not go unnoticed, achieved fame 
by letting a few mosquitoes bite him. These were not ordi- 
nary mosquitoes: they were members of the species Aedes 
aegypti, and they had fed, shortly before, on the blood of 
yellow-fever viaims. 

This event occurred in 1900, when Major Walter Reed, 
of the Army Medical Service, was checking up on the idea 
that yellow fever was carried by mosquitoes. Major Reed 
asked for volunteers who would be willing to let mosquitoes 
bite them, and 26 soldiers and doctors were selected for the 
role of human "guinea pigs." Jesse Lazear died within a 
short time, others contracted the disease but had uneventful 
recoveries, and still others, like Pvt. John R. Kissinger, whose 
obituary we have referred to, lived on in pain and suffering 
for years. In 1906, the infection in his blood paralyzed 
Kissinger from the waist down, and thus he remained for 40 
years. It is interesting to note that this man, who did so 
much for others, never looked upon himself as a hero. He 
refused all offers of money except the $125 a month disabled 
veteran's pension. How different his attitude was from that 
of some of the so-called "heroes" of the recent war, whose 
only combat experience was what they could purchase with 
a candy bar, and yet who feel that for their contributions to 
international relationships they should be supported by a 
grateful government for the rest of their lives. 

Yellow fever probably originated in Africa, where there 
is a large endenic yellow-fever area extending 3,000 miles 
eastward from the west coast to the upper Nile. From here 
apparently it was carried to the New World on the slave 
ships along with their suffering human cargo. The Spanish 
colonies reported yellow fever as early as 1648, and in the 
years since then it has taken many lives in lands around the 

Man's Mortal Enemies 23 

Caribbean. In 1801, Napoleon sent General Leclere with 
25,000 men to Haiti to put down the revolt of the negroes 
led by Toussaint I'Ouverture. The ill-equipped negroes were 
no match for the French troops and were easily defeated and 
driven into the interior. But then, yellow fever broke out, 
22,000 Frenchmen died, and the 3,000 survivors evacuated 
the island in 1803. Thus, the Republic of Haiti was born, 
thanks to the mosquito! 

The United States has not been free from yellow fever, 
although this disease, unlike malaria, has never become es- 
tablished here. Sailing ships from the West Indies often 
brought yellow fever into North American ports, particularly 
in colonial days. Cities as far north as Portland, Maine, have 
had yellow fever epidemics. In 1793, an epidemic killed 10 
percent of the population of Philadelphia, and the disease re- 
turned six years later. A severe epidemic swept Memphis, 
Charleston, and Galveston in 1878, and in 1905 New Or- 
leans felt the fury of a sudden attack. 

During the Spanish-American War, our troops in Cuba 
encountered yellow fever as well as malaria, and at that time 
the cause of the disease was unknown. Because of the seri- 
ousness of the disease, something had to be done, and the 
Yellow Fever Commission was organized to track down the 
unknown killer. As was related previously, Walter Reed 
and his co-workers proved — but not until after the war was 
over — that the Aedes aegypti mosquito was the offender. 
This information came in very handy later when the Army 
engineers set to work to build a canal across the Isthmus of 
Panama. The French had made earlier attempts to build 
a canal there, but had to give up their efforts when yellow 
fever got in its deadly work. To the Americans, it was ob- 
vious that the first task was the elimination of the mosquito. 

24 DDT — ^Killer of Killers 

By draining swamps and covering other bodies of water with 
oil, this was accomplished, and the Panama Canal was built. 

Yellow fever is by no means as widespread as malaria, 
and the yellow fever mosquito is much easier to control than 
his malaria-carrying relative. The first frost kills Aedes 
aegypti; therefore, the disease can only become established in 
climates where it is warm all-year round. The breeding 
habits of the insects also make control relatively easy. These 
mosquitoes are very sociable: they like to live near man. In- 
stead of preferring to breed in out-of-the-way swamps or 
lakes, they breed in cisterns, water-barrels, flower vases, and 
other small bodies of water around the house or barn. Thus, 
just by seeing to it that there is no stagnant water — unless 
it is covered with oil — around the premises, we can eliminate 
this mosquito. 

When a study of the breeding habits of the yellow fever 
mosquito showed that the insect could be readily controlled, 
many people began to envisage a yellow fever-free world. 
The success at Panama and the fact that yellow fever was 
eliminated from Cuba within a year after the discovery that 
the disease was transmitted by mosquitoes were certainly rea- 
sons for supporting this belief. And when yellow fever 
was eliminated from Rio de Janeiro and other places, every- 
one was convinced that with proper efforts success could be 
achieved within a very short time. 

But dreams of a yellow fever-free world proved to be 
as futile as dreams of a world free from war. If every yellow 
fever mosquito within miles of human habitation were killed, 
if not a single himian being on earth had the disease, it would 
still not be enough. The disease is not the exclusive prop- 
erty of man — it is shared by monkeys and possibly other ani- 
mals. The jungles of the world act as huge reservoirs of the 

Man's Mortal Enemies 25 

disease, and if at any time we relax our vigilance, Yellow 
Jack might slink out of the jungles and renew his deadly 

Animals, Insects, and Man 

Everyone with a dog, a cat, a flock of chickens, or a herd 
of cows knows that animals, as well as humans, get sick. But 
we are inclined to overlook the fact that animals may suffer 
from the same diseases that affect us. Since the infectious 
nature of disease was first established, we have often fallen 
into the trap of believing that we could always prevent the 
spread of a disease by keeping the sick out of contact with the 
well. But what good does that do if the disease is not 
spread by personal contact but by means of an insect? And 
worse yet, what if the insects don't carry the disease directly 
from person to person but, instead, transfer it from some ani- 
mal to a human? Maybe your pet dog is carrying a disease 
that will some day be transferred to you. Don't say that's 
impossible because your dog is in the best of health. Re- 
member Typhoid Mary and all the other typhoid carriers 
who show no symptoms of the disease yet can pass it on in 
deadly form to others. 

Our knowledge of plague, typhus, malaria, and yellow 
fever should be enough to convince us beyond doubt that our 
animal population constitutes a reservoir of disease of appall- 
ing proportions. But that is only part of the story. How 
many other diseases come to us over the animal-insect-man 
bridge? That's hard to say! For some diseases, the chain 
of events has been proved; for others it is suspected; and for 
still others, although there is as yet no evidence of an animal 
origin, the possibility is by no means remote. How else can 

26 DDT — Killer of Killers 

we account for the fact that some diseases flare up in different 
parts of the country at about the same time or within a very 
short time? To attribute this to human carriers doesn't seem 
logical, for often remote localities that haven't encountered 
an outsider in months are no safer than populous cities to 
which visitors come every day from all parts of the country. 
And why is it that many diseases flourish only in the summer- 
time and subside with the return of cold weather? Logic 
tells us that the relationship between warm weather, inseas, 
and certain diseases is more than a mere coincidence. 

In the summer of 1946, a poliomyelitis epidemic swept 
the country — the worst epidemic since 1916. A disease of 
unknown origin was again on the rampage. Although the 
total number of deaths from polio is not large compared to 
the deaths from other diseases, the mysterious nature of this 
pestilence plus the fact that it leaves many of its victims 
cripples for the rest of their lives, make it probably the most 
dreaded disease in America today. In the case of polio it is 
difficult, indeed, to attribute the spread of the disease to direct 
transmission of the virus from one person to another. Since 
polio and flies flourish at the same time, many students of 
the disease have suspected that flies are the transmitting 
agents. There is no direct evidence of this as yet, but the 
virus of polio has been found in flies, and the disease has been 
transmitted from flies to experimental animals. But this 
still leaves the question of where the disease lurks during the 
winter months. Is it possible that animals, or perhaps birds, 
harbor the disease in an unrecognizable form, and that flies 
pick up the virus from the stools of these carriers and trans- 
port it to the food of prospective victims? Is the fly respon- 
sible for the spread of the various dysenteries that masquerade 
under the quaint name of "intestinal flu"? It's possible! 

Man's Mortal Enemies 27 

After all, the fly is known to transmit the disease of pink eye 
in cattle. 

But let's look at a few diseases that are no longer in the 
realm of speculation. Rocky Mountain spotted fever is a 
disease very much like typhus. It attacks hunters, campers, 
and lumberjacks — ^people who go out into the woods and 
fields. The organism of this disease, like that of typhus, be- 
longs to the Rickettsiae family. In faa, it was Ricketts him- 
self who proved that the bite of the wood tick was the means 
by which men contracted the disease. But what animal was 
the reservoir of the disease? Ricketts' death at the age of 39 
brought to an end his brilliant investigations, but many others 
took up the challenge, and during the past 40 years many 
thousands of wild animals have been examined in attempts 
to determine the culprit. One man who has trailed the elu- 
sive killer for the past 25 years is William L. Jellison of the 
U. S. Public Health Service. Jellison's investigations indi- 
cate that the probable host is a rabbit, Nuttall's cottontail and 
perhaps some related species. 

But don't get the idea that spotted fever is limited to 
the Rocky Mountain region. This disease, or modified forms 
of it, has claimed victims in at least 41 of our states, and it 
has been spreading even to the cities. The summer of 1946 
brought an attack of an eastern form of spotted fever to the 
Borough of Queens in New York, where, during a period of 
three months, 36 persons, ranging in age from three months 
to 72 years, contraaed the disease. Undoubtedly, ticks 
spread the disease. But did the ticks get it from an innocent- 
looking cottontail, or did they pick it up from some other ro- 
dent, or perhaps a domesticated animal? 

Worse than polio in its mortality is encephalitis — liter- 
ally inflammation of the brain. This disease is world-wide 

28 DDT — Killer of Killers 

in its spread. A severe epidemic broke out in Vienna in 
1916, spread over Europe, reached Great Britain, hopped the 
ocean to North America, and appeared in about half of the 
states of the U. S. A. by May, 1920. Australia had epidemics 
in I917-I9I8 and again in 1922 and 1926. In the summer 
of 1934, 60% of the over 7,000 viaims in Japan died, and 
another epidemic broke out in Japan in the following year. 
The United States had a widespread epidemic in 1933, and 
has had a number of localized epidemics since. And the 
disease is not limited to man, for horses and sheep are also 

For many years, the mosquito has been suspected of be- 
ing the transmitting agent, and this ^as recently proved by 
Doctors W. H. Hammon and W. C. Reeves of the Hooper 
Foundation for Medical Research, University of California. 
Of the many thousands of different kinds of insects that these 
men and their co-workers collected, only the mosquito was 
found guilty of carrying the virus. And even more startling 
was the proof that birds, both wild and domesticated, are the 
reservoirs of the disease. That is why most cases of en- 
cephalitis occur in rural areas, small towns, and suburbs of 
large cities — ^places where people keep chickens. 

We could go on and on and show the possible animal- 
insea-man relationship in the transmission of many other 
diseases, but we shall bring this section to a close with a few 
words about African sleeping sickness. This disease is car- 
ried by the tsetse fly, and it affeas animals as well as man. 
The only way to control the spread of the disease is to elimi- 
nate the flies, or at least to confine them to areas far from 
human habitation. That is why a news item from Pretoria, 
South Africa, dated July 21, 1946, is of particular interest. 
Briefly, this article stated that the biggest wild animal hunt in 

Man's Mortal Enemies 29 

the history of Africa would begin the next day. All wild 
game — warthog, buffalo, and zebra — over an area of 400 
square miles of Zululand were to be rounded up and trans- 
ported to a specially prepared reserve. And a strip two 
miles wide was to be laid waste around the reserve, on the 
assumption that the tsetse cannot fly that distance. That is 
a drastic procedure! 

But what are we in this country going to do? Will we 
be forced to exterminate the wild animals of our woods, or 
confine them in special reserves? Will the raising of chick- 
ens be restriaed to certain regions of the country, and the 
area be placed under strict quarantine? Will it be consi- 
ered a criminal offense to keep a dog or cat or perhaps a rab- 
bit? Will horse racing finally be barred, not because of the 
evils of gambling, but because horses carry disease? There 
are legitimate arguments for doing all of these things. But 
wouldn't it be much simpler if we would just concentrate on 
getting rid of the insects that carry the diseases from animals 
to man? And remember this: don't be misled by the as- 
sumption that "it's just a harmless insea." How do you 
know it's harmless? Just because there is as yet no proof 
that a particular insea is harmful does not mean that it is 
harmless. When a man is brought into a court of law, we 
assume that he is innocent unless he is proved guilty. This 
is a sensible attitude for it does give greater protection to in- 
nocent people, even though, unfortunately, it also permits 
many of our gangsters and other public enemies to escape 
punishment for their crimes. But, be this as it may, when 
we deal with insects, the only wise thing to do is to assume 
that they are guilty unless they are proved innocent. 

Chapter Two 

DDT is Born 

Unwepf, Unhanored, and Unsung 


ESTINED to live a life of virtual obscur- 
ity and to die unaware that he held within his grasp the key 
to fame and fortune — that was the fate of Othmar Zeidler. 
For almost seventy years, while millions of people on the face 
of the earth died in agony from the bites of lice, flies, fleas, 
mosquitoes, and other insects, the chemical formula of a 
white, crystalline substance that could have saved these lives 
was available to anyone who had the curiosity to look for it. 
But no one bothered to thumb through the dusty volume of 
the Berichte der Chemischen Gezellschaft — The Proceedings 
of the German Chemical Society — for the year 1874, and to 
read the six obscure lines of type that described the prepara- 
tion of dichloro-diphenyl-trichloroethane — DDT to you — by 
Othmar Zeidler, a young chemistry s^dent^t Strasbourg, 

After all, Zeidler himself had little interest in what he 
had done. Like thousands of other chemistry students who 
have gone through the ordeal known as "working for a de- 
gree," Zeidler had to prepare a thesis, an uninspiring task at 
which a student slaves away in a routine manner until he ac- 
cumulates enough data to "write-up" and submit to his pro- 
fessors, who, feeling that the poor student has been punished 


DDT Is Born 31 

enough, then grant him his degree. It was in just this rou- 
tine fashion that Zeidler reacted chloral hydrate — known in 
disreputable circles as knockout drops or Mickey Finn — and 
chlorobenzene, in the presence of sulfuric acid, and obtained 
the product he described^ He had completed his task; he 
had added another organic compound to the rapidly growing 
list — a list that now comprises several hundred thousand 
compounds and is growing longer every day. 

To Zeidler, his product was just like many others, ex- 
cept, of course, that the various atoms of carbon, hydrogen, 
and chlorine were hooked up in a somewhat different pat- 
tern than they were in any other compound. How could he 
know that his particular pattern of atoms carried potential 
death to many of man's most formidable enemies? Just 
think how the course of events might have been changed if, 
on that day in 1874, a fly buzzing around a laboratory in 
Strasbourg had decided to investigate the nice white precipi- 
tate that Zeidler had obtained! Suppose that a fly had lit on 
this first sample of DDT. Do you believe that Zeidler 
would have watched the curious creature stagger around like 
a drunken sailor and then drop dead? No, he would prob- 
ably have been so outraged at the presumptuousness of an 
insect that dared to contaminate the product of his careful la- 
bors that he would have smacked the little fly dead before it 
had a chance to exhibit the symptoms of DDT poisoning. 
So let's not blame Zeidler for not discovering the magical 
^wers of the suBstanceTie prepared. Undoubtedly, in other 
dusty volumes~on th e shelves^ of our libraries, there^an^ 
found the formulas of numerous other, and even more, magi- 
cal substances — substances capable of curing the worst ills of 
man — with properties as yet unrecognized. Perhaps some 
day when the cure for cancer or tuberculosis is found, we may 

32 DDT— Killer of Killers 

delve back through the years and find that long, long ago the 
self -same formula had been worked out by some other ob- 
scure chemistry student while working on his thesis. 

The Lost is Found 

Contrary to common opinion, great scientific discoveries 
are seldom the result of accident. Instead, they result from 
carefully planned programs of research in which a large num- 
ber of scientists usually collaborate. DDT was no excep- 
tion. Although Zeidler had prepared DDT many years ago, 
he was not looking for an insecticide and was in no position 
to recognize one when it suddenly appeared in his test tube. 
It remained for a large chemical company and teams of 
trained research scientists to give to the world this remark- 
able discovery. 

In about the year 1934, in the scientific laboratories of 
JLR. Geigy, A. G., of Basle, Switzerland, a team of workers 
began a series of investigations aimed toward the develop- 
ment of more potent insecticides. They tested the effeaive- 
ness of a large number of available insecticides; they selected 
those that showed the greatest promise; and then they syn- 
thesized a large number of new materials in order to deter- 
mine the effect of different arrangements of the atoms. 
Among these investigators was Dr. Paul Mliller, and one of 
the products he synthesized proved to be of startling effec- 
tiveness. Unknown to Miiller, this compound was identical 
with the white, crystalline substance prepared years before 
by Zeidler. Laboratory tests of this new insecticide against 
flies and the larvae of clothes moths showed that it had great 
potentialities, but many materials which survive laboratory 

DDT Is Born 33 

tests reveal unexpected limitations when used on a large 
scale under actual field conditions. 

But DDT did not have to wait long to prove its worth. 
In the year 1939, the potato crop of Switzerland was threat- 
ened with devastation by an unwanted immigrant from the 
United States — the Colorado potato beetle. Something had 
to be done in a hurry, and something was done! _Asjl re- 
sult of their experiments, Geigy felt that their new inseai- 
cide might be the answer, and they supplied Dr. R. Wies- 
mann, a Swiss entomologist, with a quantity of their "Experi- 
ment No. G 1750" — later called Gesarol. Wiesmann tried 
out this produa — a 1 % DDT dust — at the Swiss Federal Ex- 
perimental Agricultural Station at Waederswill, where its 
remarkable insecticidal properties were verified. Then, out 
into the fields it went; the Swis^ potato crop was saved; and 
the magic letters DDT were soon destined to become a com- 
mon household expression throughout the world. 

Soon the world was to be embroiled in a conflict of 
unimagined proportions. Man was destined to kill his fel- 
low man on battlefields throughout the world. Many 
American boys, brought up in a country where the standards 
of sanitation are the highest in the world, were soon to be 
sent to many lands where the menace of typhus and other 
dreaded diseases awaited them. Medical men were well 
aware of the serious implications of the situation, and our 
medical resources were rapidly mustered to study means to 
save our military men from the fate that had befallen so 
many armies in the past. The experiments of Geigy in 
Switzerland had shown that DDT was an amazingly effective 
killer of the louse — that tiny insect that carries the dreaded 
typhus. In August 1942, Geigy informed Major De Jonge, 
American military attache in Berne, Switzerland, of their 

34 DDT— Killer of Killers 

amazing results, and at the same time it forwarded this in- 
formation to its American subsidiary, Geigy G)mpany, Inc., 
in New York. It would be nice at this point if we could re- 
peat the highly dramatic but totally false story that appeared 
in some of our newspapers to the eifect that a quantity of 
DDT was smuggled out of Switzerland in the best tradition 
of a wartime spy thriller. However, the prosaic truth is that 
the DDT was merely sent through regular channels from 
Geigy in Switzerland to Geigy in New York. 

When Geigy in New York received this first shipment 
of DDT, it submitted samples to the U. S. Department of 
Agriculture for testing. The results were phenomenal, and 
another 200 pounds of DDT were imported from Switzer- 
land and distributed to various Department of Agriculture 
Experimental Stations throughout the United States. From 
every source came startling confirmation of Geigy's claims. 

Colonel William S. Stone of the Surgeon General's Of- 
fice was quick to realize how important it was to our armed 
forces to have this miracle killer. At Orlando, Florida, 29 
scientists, at the experiment station there, were assigned to 
devote their entire energies to the development of DDT com- 
positions for military uses. To these 29 men — many of 
whom remain anonymous — many Italian citizens as well as 
American troops owe their lives. It is the common fate of 
technical men to go unrecognized for their efforts in behalf 
of humanity, but we can at least express our appreciation to 
three of the men, Dr. F. C. Bishop, Dr. Walter E. Dove and 
Mr. E. F. Knipling, who played such an important role in 
developing military uses for DDT. 

The value of DDT to our armed forces was soon clearly 
demonstrated. Now it had to be turned out on a large scale. 
American industry accepted the challenge in the same spirit 



Fig. 3. Youngsters are Treated with DDT Powder During 

THE Army Medical Service's Successful Campaign to 

Stop the Typhus Epidemic in Naples in Early 1944. 

(Courtesy of Geigy Company, Inc.) 



Fig. 4. Captain Arthur W. Hill of Washington, D. C, and 
T/5 Joseph Russotto of Bayonne, New Jersey, Apply Louse- 
Killing DDT Powder to an Arab Family at L'Arba in Algeria. 

{Courtesy of Prev. Med. Serv., Surgeon General's Office) 



Fig. 5. Colonel W. S. ^tonl Dusts an Arab with DDT 
Louse Powder, 

( Courtesy of Prev. Med. Sen., Surgeon General's Office) 



Fig. 6. This Soldier Won't Be Bothered by Lice After His 
Dusting With DDT Powder. 

(Courtesy of Geigy Company, Inc.) 


DDT Is Born 39 

with which it had taken on so many other seemingly insur- 
mountable problems during the war. In 1943, DDT was 
in commercial produaion at the Cincinnati Chemical Works, 
a subsidiary of Geigy Company, Inc., and early in 1944, Du 
Pont, Merck, and Hercules Powder Co. also went into pro- 
duction. In fact, within a short time, 15 American chemical 
companies were producing DDT for our armed forces; and 
another problem had been licked through American ingenu- 

Although there are a large number of manufacturers of 
DDT, the use of this substance in inseaicidal preparations is 
covered by patents issued to Geigy in various countries, in- 
cluding Switzerland, England, Canada, and the United States. 
To make this magic insecticide available to everyone, Geigy 
has followed a very liberal licensing policy. Manufacturers 
of insecticide compositions containing DDT are licensed un- 
der the Geigy patents and pay a nominal fee for this right — 
a fee that is remarkably low when one considers the tremen- 
dous cost of the many years of development work by this 

What Is DDT? 

To the average individual, DDT is a material that is 
used to squirt the obnoxious fly and mosquito so as to shorten 
the days of their lives; or it is a powdery material dusted down 
the pants of a dirty individual in order to kill lice. Actually, 
to call either of these materials DDT is not strictly correct, 
for pure DDT is never used as such but is always compounded 
with other ingredients to form the various sprays or powders 
that are now being sold throughout the country. You won't 
find pure DDT in the corner store. If you want to see it, you 

40 DDT— Killer of Killers 

must go to the factory where it is being manufactured or 

But what is DDT? To you it is a killer of insea life. 
To the chemist, it is a compound of carbon, hydrogen, and 
chlorine, represented by the following structural formula. 

and bearing the name dichloro-diphenyl-trichloroethane. It 
is easy to see from the jaw-breaking length of this chemical 
name that a drastic abbreviation was necessary. An official 
of the British Ministry of Supply got tired of writing this 
long chemical name, and early in 1943 earned the gratitude 
of many suffering stenographers by substituting the simple 
letters DDT. And DDT it has been ever since. 

Pure DDT, as designated by the above formula, is a 
white, crystalline powder with a weak, fruit-like odor, and 
having a melting point of 107-108 °C. The commercial 
product, however, melts as low as 88°C., due to the presence 
of so-called isomers, that is, compounds having the same 
number of carbon, hydrogen, and chlorine atoms as shown 
in the above formula but arranged in a slightly different man- 
ner. These isomers don't harm the product, for they also 
possess insecticidal properties. 

If you should be interested in making some DDT, you 
could follow the instructions which appear in a 1942 British 
Patent issued to J. R. Geigy, A. G. : 

"225 parts of chlorobenzene are mixed v/ith 147 parts 
of chloral or the corresponding amount of chloral hydrate 

DDT Is Born 41 

and then 1,000 parts of sulfuric acid monohydrate are 
added. Whilst stirring well, the temperature rises to 60°C. 
and then sinks slowly down to room temperature, the mass 
then containing solid parts. It is poured into a great deal of 
water, whereupon the product separates in solid form. It is 
well washed and crystallized from ethyl alcohol forming fine 
white crystals, having a weak fruit-like odour." 

In 1945, almost 33 million pounds of DDT were pro- 
duced in the United States, and for practically the entire out- 
put, batch processes similar to that described above were em- 
ployed. Production was stepped up even higher in 1946, 
but the method of manufacture has remained virtually un- 
changed. To the chemical engineers in the industry, this 
has been rather disconcerting, for every time a chemical en- 
gineer encounters a batch process he gets an almost uncon- 
trollable desire to replace it with a continuous process, and 
thus decrease the cost of manufacture. Engineers lost no time 
in applying their skills to DDT manufacture; and it was not 
long before continuous processes were announced. But, ap- 
parently, all the problems associated with continuous manu- 
facture have not yet been solved; at least, no continuous 
process is, as yet, in commercial operation on a large scale. 

DDT is insoluble in water, and this property has an im- 
portant bearing on the way this insecticide has to be formu- 
lated. Since you can't dissolve DDT in water, you must 
dissolve it in some organic solvent in order to obtain a product 
that you can spray around the house. Numerous solvents 
can be used, but the most common — because of its low cost 
^ — is kerosene or some other petroleum distillate. Of course, 
for many applications it is not necessary to use DDT in solu- 
tion form — it is often advantageous to apply it in the form 
of a powder. But even for application in this form, you 
couldn't use 100 % DDT even if you wanted to. The crystals 

42 DDT— Killer of Killers 

of DDT are very waxy, and this makes it impossible to grind 
^i them to a fine powder. However, if DDT is ground with 
If pyrophyllite, talc, or some forms of clay, a finely-divided, uni- 
^form, and fr<^ gj[Qwing^po wder res ults. 

Free Enterprise 

It was the summer of 1945, and the civilian population 
of the United States, having heard of the wonders of DDT 
on the battlefields of the earth, was waiting, almost breath- 
lessly, to get some of this white magic to fight their own 
battles against the fly, the mosquito, and other insect pests. 
But the War Produaion Board said "No!" Although Ger- 
many had been defeated, there was still a war on with Japan; 
and the armed forces, of course, had the No. 1 priority on 
this wonder killer. 

Manufacturers of DDT, according to the regulations 
of the W. P. B., could release only 5 per cent of their output 
for civilian purposes — the rest had to be reserved for the 
armed forces. In view of the unprecedented demand, 5 per 
cent was even less than the proverbial "drop in the bucket." 

But the picture suddenly changed. A smart young 
chemist named Walter Steuber, of Swarthmore, Pennsylvania, 
decided to cash in on this ready market. Like other chemists, 
he knew the formula for DDT and how it could be made. 
Furthermore, he knew that the raw materials — chloral hy- 
drate, monochlorobenzene, and sulfuric acid — could be ob- 
tained at that time without priorities at the corner drugstore. 
So he converted the cellar of his house into a miniature 
chemical plant, and started flooding the suburbs of Philadel- 
phia with DDT solution at $1.00 per pint — paying no at- 

DDT Is Born 43 

tention whatever to W. P. B.'s 5 per cent limitation. The 
public rushed to buy; and Mr. Steuber made a handsome 

The W. P. B., however, was mighty displeased with this 
flagrant flouting of its regulations, and the regular manu- 
facturers of DDT, who had been anxiously awaiting the 
start of the race for the civilian market, were not happy to see 
a competitor — even though he operated on an insignificant 
scale — ^get the jump on them. It would have been easy to 
crack down on Mr. Steuber, but the W. P. B. decided, very 
sensibly, to permit all manufacturers to sell a much higher 
percentage of their output for civilian purposes. The battle 
for the domestic market was now on. Soon, DDT prepara- 
tions, under numerous names and formulated by various com- 
panies, were appearing in store windows all over America. 

Chapter Three 

Not Too Hot to Handle 

Did If Taste Good? 

ITXE felt very nervous and sick at the stom- 
ach. Then he began to vomit. Something was wrong with 
his jaws: they were painful and felt stiif. The trouble seemed 
to start when he took that last chew of tobacco a few hours be- 
fore. But how could that cause it? He had chewed tobacco for 
years — that same brand of plug — and had never noticed any- 
thing like it before. Perhaps his quid did taste slightly dif- 
ferent than usual, but then, when you carry a plug of tobacco 
around in your pants pocket along with everything else you 
put in your pocket during the day, you can't expect it to taste 
the same every time you bite off a chunk. After all, a farm 
hand can't be too particular; he can't throw his plug of to- 
bacco away just because it gets a little dirt on it. 

But the doctor was curious; he had never before en- 
countered this combination of symptoms. However, the sore 
jaws, the twitchings, the muscular tremors, and the nervous-, 
ness had been observed by a number of investigators when 
they administered toxic doses of DDT to experimental ani- 
mals. Had this man been using DDT? As a matter of fact 
he had carried around a bottle of a DDT-kerosene solution 
earlier in the day. And he had carried it in the same pocket 
where he kept his tobacco! Could the stopper have come 


Not Tcx) Hot To Handle 45 

loose and could some of the liquid have leaked out onto the 
tobacco? This was, at least, a possibility. Did he have 
DDT poisoning? Better check up! Sure enough, his urine 
showed DDT! 

The farm hand soon felt better and was able to get 
back to work, although his throat felt sore for about three 
days. Whether or not he learned his lesson and took better 
care of his plug of^tobacco in the future is not part jof the 

This enlightening experiment in the spring of 1946, 
although entirely unintentional, was certainly very valuable 
for it was the first authentic report of the toxicity of DDT on 
man. It was recorded for posterity in the Journal of the 
American Medical Association by Dr. M. I. Smith, of the 
National Institute of Health in Bethesda, Md. 

From a purely scientific point of view, this experiment 
left much to be desired: there was no record of the amount 
of DDT that this lover of tobacco had consumed. Never- 
theless, it must have been many times the amount that anyone 
would be likely to get accidentally under even the most care- 
less conditions of use. Actually, among all the hundreds of 
workers engaged in making DDT, in formulating sprays and 
powders, and in testing the products over periods of months, 
no case of DDT poisoning has yet been reported. But, let's 
look into this matter of toxicity a little more thoroughly. 

Don't Be Afraid! 

Something that will kill bugs may also kill animals, 
even man. This sounds logical enough, but it isn't necessar- 
ily true. However, it's hard to convince some folks of that. 
And when DDT first hit the civilian market, many people 

46 DDT — Killer of Killers 

were afraid to handle iu This, in part, was due to the fact 
that DDT was a relatively new material and neither the man- 
ufacturers themselves nor the governmental agencies that 
were working with it had had sufficient time to learn all about 
it. Of course, it was known that DDT was somewhat toxic 
to many of the lower animals, but experiments were still in- 
conclusive. But what of its effea on man? Would a single 
large dose kill? Would a number of small doses taken at 
intervals over a period of time have a cumulative effea that 
:would eventually result in death even though a single dose 
produced no toxic symptoms? 

Obviously, few men are so constituted that they will aa 
as human guinea pigs so that the world may get the answers 
to such important questions. A more indirea approach must 
be used. Rats, mice, rabbits, cats, dogs, and numerous other 
animals must take the place of man himself and be the un- 
willing test animals. The manufacturers as well as various 
governmental agencies lost no time in rounding up a number 
of these animals and forcing DDT down their throats, inject- 
ing it into their bodies, and applying it to their skins. 

But all such tests take time, particularly if one is study- 
ing the cumulative effects of small doses of a substance taken 
at intervals. Should DDT have been kept off the market un- 
til years had elapsed and enough data had been collected to 
determine without doubt just exaaly how poisonous it was? 
This would have been senseless, for in the meantime the in- 
seas would have been able to continue their deadly work. It 
was certainly much better to release the material to the public 
with a word of caution as to its possible dangers. Let people 
use it, but let them also realize that they should also use 
common sense in handling it. That was the attitude of the 
U. S. Department of Agriculture, Produaion and Marketing 

Not Too Hot To Handle 47 

Administration, Livestock Branch, which casts an eagle eye 
on the labels of all inseaicides sold in interstate commerce 
to see to it that no false claims are made and to make certain 
that the purchaser is fully informed as to all safety precau- 
tions he must observe when handling the inseaicide. 

Avoid excessive inhalation of the spray or dust! Do 
not contaminate foodstuffs! If a solution of DDT is acci- 
dentally spilled on the skin, wash it off with soap and water! 
That is all that is demanded in the way of caution, except of 
course, the usual one in the case of inflammable liquids — 
avoid fire or open flame! There is nothing in these state- 
ments that should have frightened anyone. Of course you 
should avoid inhaling insect sprays: most of them contain 
petroleum solvents which themselves can make you slightly 
sick if you imbibe or inhale enough. For that matter, you 
shouldn't breathe any more gasoline fumes or the fumes of 
cleaning fluids than you can help. As for avoiding contamin- 
ation of foodstuffs, that also makes sense. You try to keep 
dust and dirt from getting mixed up with the various in- 
gredients you use in making a cake, so why shouldn't you 
also keep DDT out of your food? As for washing your 
hands when you spill some DDT solution on them, that is 
not as essential as you may have been led to believe, but never- 
theless, it's always a good idea to keep your hands clean. 

How Much is Fatal? 

Since no one has ever died from DDT poisoning, k is 
diflicult to say just what a toxic dose is. If we assume that 
dogs, cats, and other small animals react in the same way to 
DDT as does man, we can get some idea. At least we can 
find out enough to alleviate our fears. Let's start out with 

48 DDT— Killer of Killers 

rats, who seem to resemble man rather closely in their reac- 
tions to various disease organisms and poisons. There is no 
point in reviewing the results of hundreds of experiments, 
but let's take a typical one. A number of rats were given a 
total of 1.2 grams of DDT in % gram doses per day over 
a six-day period, and then were watched for six months 
to see ii they would exhibit signs of poisoning. They did 
not! In all respects they appeared perfealy normal. Now, 
these rats weighed an average of 300 grams each, or % 
pound. If a man could tolerate the same dosage in pro- 
portion to his weight, then a 150-pound man could take 
120 grams, or more than /4 pound, of DDT over a period 
of six days without any ill effects. Or, to put it another 
way, he could eat over 2"^ pounds of a 10% DDT dust. 

Or do you resemble a mouse more closely than you do a 
rat? In that case, you will be more interested in the ex- 
periments on four white mice, each weighing 10 grams, 
which were fed 0.015 grams of DDT (0.003 grams per day 
for five days ) . Thirty days later they appeared quite normal. 
Again extrapolating to find out how a 150-pound man would 
fare, we find that he could take 102 grams, or slightly less 
than /4 pound, over five days and remain perfectly healthy. 

Since some folks are reputed to take after the cat, we 
shall see what they might expect. ^ One cat was fed a total of 
315 milligrams and another 480 milligrams in six different 
doses, without any sign of poisoning. The experimenters, 
however, neglected to report the weight of the cats. So we 
scouted the neighborhood and picked up a typical alley cat, 
and found that he weighed 10 pounds. Thus, 15 alley cats 
are equivalent in weight to a 150-pound man. If one cat 
can take 480 milligrams of DDT, a man should be able to 
take 15 times that much, or 7,200 milligrams (7.2 grams; 

Not Too Hot To Handle 49 

0.015 pound). Judging from the experiments above with 
rats and mice as the test animals, a man could safely eat a lot 
more DDT than this. Apparently the cats could have toler- 
ated, without discomfort, many times the quantity of DDT 
they were given. 

For the dog lover, we have the experiment in which two 
dogs were fed 5 grams of a 5 % DDT mixture per day for 
each 5 to 6 kilograms of body weight over a period of 31 
days, with no sign of poisoning to man's best friend. This 
quantity figures out to be about 3.1 grams of actual DDT per ■ 
day for a 150-pound man, or about 100 grams — slightly less ' 
than /4 pound — for the 31 -day period. 

The sheep-like individual can take heart in the tests 
carried out on one of the members of this gentle tribe at the 
University of Southern California. This placid creature was 
fed, along with his regular food, 2 grams of DDT per day for 
1 1 days, 4 grams per day for the next 40 days, and then 8 
grams per day for the next two weeks. He thrived on the 

The results of these and many other experiments show 
what? Simply this: The quantity of DDT required to kill 
a person, or even to make him sick, is very great. Although 
everyone should have sense enough not to use an insect spray 
where it might contaminate food, it is highly improbable that 
eventEe most careless person could possibly get enough DDT 
on his food to endanger his health. Certainly DDT is much 
less toxic to warm-blooded animals than are many of the 
common agricultural inseaicides, such as the arsenicals, and 
lead and fluorine compounds. 

Will DDT Poison Warm- Blooded Animals? 

It would be a gross mistake to leave one with the im- 

50 DDT— Killer of Killers 

pression that DDT is harmless to man and other animals. 

It will poison and eventually kill if a lot of it is eaten over a 

'long period of time. For example, rats fed one part of DDT 

tin 10,000 parts of foodstuffs began to have convulsions after 

I two months, and died within a few days thereafter. Other 

rats and mice fed on diets containing 0.05 % DDT showed 

, definite signs of poisoning after long periods of time. And 

I sheep put out to graze in a pasture treated 48 hours previous- 

I ly with 40 pounds per acre of 10 % DDT dust showed neuro- 

! logical symptoms after about 3 days, although none died. 

Mice, guinea pigs, dogs, cows, horses, and rabbits — in 
addition to rats and sheep — have been given sufficient DDT 
over periods long enough to kill them, or at least to make 
them sick. The different species of animals showed marked 
differences in their susceptibility among different individuals 
of the same species. The same is probably true with men, for 
one man's meat is often another man's poison. Some of the 
less reputable members of human society have been known, 
on occasion, to drink copious quantities of automobile anti- 
freeze and other equally unattraaive concoctions. Some of 
these individuals seem to thrive on such a liquid diet, while 
others with less rugged constitutions soon lose more than just 
a week-end. 

In general, when an animal gets too much DDT he loses 
his appetite, his nervous system goes hajrsvire, and he gets the 
tremors; and finally, if he has had a sufficiently large dose, he 
gets convulsions and dies. Autopsies usually reveal fatty de- 
generation of the liver and kidneys and changes in the ner- 
vous system, but with no apparent damage to the brain and 
spinal cord. But this requires a massive dose of from 150 to 
750 milligrams of DDT per kilogram of body weight, de- 
pending upon the animal, and this is equivalent to about 10 

Not Too Hot To Handle 51 

to 50 grams (about % to 1% 02.) for our 150-pound man. 
Do Y(Ni Inhale? 

When you chase the pesky fly around with a squirt gun 
and finally let him have it, you can notice the mist that en- 
gulfs the hapless insect. If you watch closely, you can see 
some of the fine, misty particles taking their time in settling 
to the floor. If you happen to inhale while in the midst of 
these minute, setxlmg droplets, it is inevitable that some of 
them will enter your nasal passages. Should you rush to the 
phone and call the doctor or just quietly lie down and wait 
for the end? Unless you're a hopeless neurotic, you'll just 
forget the whole thing and go ab out your business looking 
for more flies. 

When DDT fly sprays first appeared on the market, 
some department stores were guilty of some very poor psy- 
chology. They not only offered a word of caution, but they 
practically scared the daylights out of their customers by 
warning them to put masks over their faces, to wear rubber 
gloves, and to say good-bye to all their friends and relatives 
before taking the innocent looking spray gun in their hands. 
Is it any wonder, then, that many timid souls shrank from 
the DDT mist as they would from the open sores of a leper? 
It is all right to be careful — and very wise — but why overdo 

Sure, if you give an experimental animal enough DDT 
spray to inhale, he will show the same symptoms of DDT 
poisoning that he will if you shove enough down its throat. 
But how much is enough? Much more than you will ever 
inhale during your occasional attacks on the uninvited visi- 
tors to your home. Threedogs were made to breathe %o 

52 DDT — Killer of Killers 

^ram of DDT per kilogram of body weight per day over a 
period of 18 days, at the end of which time only one of the 
three animals showed signs of poisoning. At the same rate, 
our 150-pound man would have to inhale about 6.8 grams of 
^DDT per day, or over Yd pint of a 5 % DDT solution! 
About the only way he could possibly do this would be to 
squirt the spray right up his nose; and even then it would be 
a rather tedious job. If the solution contained only one per 
cent DDT, our mythical man would have to work much 
harder— he would have to inhale about a quart of the spray. 
The rabbit is not a particularly robust beast, but it has 
been found that when he is exposed to a 1 % DDT-kerosene 
spray for 48 minutes a day he is still in the best of health 
after 4 weeks. If 48 minutes a day won't bother a little rab- 
bit even when you try to make him breathe the stuff, it is 
very unlikely that you will be affeaed by breathing a little 
DDT mist for a few minutes a day. No, not even if your 
spray contains 5 % DDT instead of 1 % ! 

Your Liiy-White Skin 

Your bones and flesh are enclosed, more or less tightly, 
in a tough, thick membrane which we call the skin. Your 
usual preoccupation with this portion of your anatomy is 
principally with such matters as whether it is clean or dirty, 
whether it is firm and taut or hangs in baggy folds beneath 
your jaw bone and under your eyes, or whether it is freckled, 
pimply, full of blackheads, or needs a shave. Yet your skin 
— even if it is the type that no one loves to touch — is a very 
complicated mechanism that has many things to do. It 
holds the rest of you together; on hot days it lowers your 
body temperature by discharging perspiration to the body sur- 

Not Too Hot To Handle 53 

face where it can evaporate and thus absorb heat; on cold days 
it keeps your sweat glands closed but opens your oil glands 
so that they can secrete an oily substance which forms an in- 
sulating film over your goose pimples; and it forms a protect- 
ing barrier between your muscles and fat and the outside 
world that swarms with bacteria, fungi, and inseas. If bac- 
teria light on your unbroken skin they lead neither a merry 
life nor a long one. But just let them find an opening where 
the skin has been punaured by a bite, a cut, or a broken 
blister from your too-loose shoes, and then their ugly faces — 
if they have any — light up with smiles of triumph as they 
find an environment that is very conducive to bringing up a 
large family. 

So the skin is porous! Your perspiration — or shall we 
just say sweat? — originates within the body and passes out- 
ward, evaporating on the surface of the body or being ab- 
sorbed by your clothing; in either case, spoiling your most 
romantic moments as you wonder if you, too, have B. O. 
But don't take it too hard; maybe it is your healthy human 
smell that is responsible for your lover's passionate insistence, 
and not the few drops of essence of musk deer — at $40 per 
ounce — masquerading under a name which grandma sure 
would consider carnal. 

Now don't get the idea that just because some substances 
can pass through the skin from the inside of the body out- 
ward that the reverse journey is as readily negotiated. You 
may kid yourself that you look years younger after you "feed" 
your skin by plastering on some of Lady X's perfumed axle 
grease, but even if the stuff was any good, the quantity that 
could possibly get through the very outer layers of your epi- 
dermis would be much too insignificant to convert you from 
an old hag — who wouldn't even be whistled at by a marine 

54 DDT— Killer of Killers 

on a dark night — to a sweet young thing one jump ahead of 
the wolf pack. But before we leave the subject, just one 
more word — if you want to feed your skin, the only way to 
do it is by feeding the rest of your body, preferably by means 
of a thick steak, if you can get one. 

Why, then, all the fear of dire results when DDT solu- 
tions are spilled on the skin? Can DDT penetrate the skin? 
And if so, how much? And what does it do when it does 

DDT Crashes the Barrier 

If talcum powder passed through the skin and entered 
the body, much of the female population of the world would 
weigh a whole lot more than it does — unfortunately — at pres- 
ent. And the coal miner would have such a black interior 
that when he cut himself, a black, inky fluid would drip forth. 
No, dusts and powders cannot penetrate the skin! And 
DDT dusts and powders, or even pure DDT, are no excep- 
(tions. That is why DDT powders can be safely sprinkled 
inside one's underwear to disturb the life of the crawling 
louse. And that is why a bed sprayed with a solution of 
DDT to kill bedbugs is perfectly safe to sleep in after the 
solvent has evaporated, leaving the crystals of DDT behind. 

Let us now turn to sprays consisting of DDT dispersed 
in water. Are they dangerous to the skin? Absolutely not! 
When you go swimming, you don't become water logged — 
because water doesn't penetrate the skin. And even if water 
did penetrate to some extent, water dispersions of DDT would 
present no hazard, for the water could not carry the DDT 
with it, since DDT does not dissolve in water and the size of 
the DDT particles in a water suspension is much too great to 

Fig. 7. An Unsung Hero of the War — A Volunteer Lets 
Body Lice Feed on His Back in Experiments That Helped 
Government Agencies Develop DDT for Use Against the 
Typhus-Carrying Louse. The Lice, on Patches of Cloth, are 
Allowed to Feed on the Subjects Back and Are 
Then Removed. 

{Courtesy of U. S. Dept. of Agriculture) 


Fig. 8. There Wont be Any Flies in This Room After the 
Young Lady Finishes Spraying. 

(Courtesy of Hercules Powder Co.) 


Fig. 9. A Wise Housewife Knows That Insects Like to 
Hide in Dark Places. 

(Courtesy of Hercules Powder Co.) 



Fig. 10. There Will be No Fleas in This House After the 

Floors and Rugs are Sprayed with a 5% 

DDT-Kerosene Solution. 

(Courtesy of U. S. Dept. of Agriculture. Photo by Madeleine Osborne) 


Not Too Hot To Handle 59 

permit their passage through the minute pores of the body's 

But when we come to solutions of DDT in organic sol- 
vents, the picture is somewhat different, for there is at least a 
possibility that some organic solvents can diffuse through the 
skin. Solvents such as gasoline, kerosene, benzene, chloro- 
form, and acetone are capable of dissolving oils and waxes. 
Because of this property, it is possible that they could gradual- 
ly diffuse through the skin. Of course, if there is some DDT 
dissolved in the solvent, it would accompany the solvent on 
its journey. 

But let's try to separate some of the fact from the fiction. 
To merely state that DDT dissolved in organic solvents can 
be absorbed by the skin, without giving some idea of how 
much can be absorbed and what effect it has on the body, 
simply scares people without doing them any good. As for 
the facts: It is possible to produce symptoms of DDT poison- 
ing in experimental animals by treating their skins with solu- 
tions of DDT in organic solvents for sufficiently long periods 
of time. But, there is as yet no evidence that human beings 
have ever been poisoned in this manner. 

Laboratory workers are curious individuals: they often 
get tired of working on little animals and, to break the 
monotony or to get an answer that their guinea pigs couldn't 
give, they try their concoaions on themselves. In the spirit 
of scientific curiosity, research men have soaked cotton wicks 
in concentrated DDT solutions and stuck them on their arms 
for twenty-four hours. The results: no irritation, burning, 
or toxic reactions. And even the authors of this book have 
kept their hands and arms to the elbows covered with a 5 % 
DDT-kerosene solution for several hours and could notice no 
sign of irritation or toxicity. And when one considers that 

60 DDT— Killer of Killers 

hundreds of men and women have been engaged for months 
in the preparation and testing of DDT sprays and none has 
suffered injury, one is led, inevitably, to the conclusion that 
the danger of poisoning f roni^DDT solutions^qn the skin has 
fen grossly exaggerated. 

Although it is true that a few good experiments are 
more conclusive than lots of reasoning, let us look at the prob- 
lem from a different point of view. Although animals differ 
in their susceptibility to DDT, all the evidence points to the 
fact that a dose of less than /4o gram of DDT per kilogram 
of body weight is absolutely harmless, and many animals con- 
tinue to thrive when much higher doses than that are ad- 
ministered. Now, /4o gram per kilogram of weight means 
that our mythical 150-pound man could take at least 6.8 
grams of DDT — and probably much more — in a single dose 
without harm. As we pointed out a little while ago, it takes 

(more than a third of a pint of a 5 % DDT solution to furnish 
that much DDT; and can you imagine a third of a pint of the 
liquid being absorbed by the skin? Even if you took a bath 
; in the stuff — although we don't recommend it — it is highly 
J^ t unlikely that you would be in any danger. 

The Poor Fish 

Many of our otherwise sane citizens enjoy nothing more 
than getting up at the break of dawn on a cold spring morn- 
ing and wading through the cold waters of some favorite 
stream in the hope of tricking an innocent trout into believing 
that a bundle of gaudy feathers is good to eat. Other mem- 
bers of the piscatorial tribe brave swarms of mosquitoes and 
black flies in their attempts — often futile — to hook a prize- 
winning trout or salmon. But whether your fisherman pre- 

Not Too Hot To Handle 61 

fers trout or bass, or catfish, perch, or suckers, he takes his 
sport seriously and is much concerned about the finny popu- 
lation of our lakes and streams. 

So, when water areas are sprayed to control the mos- 
quito, or when forest areas are sprayed to control the numer- 
ous insect enemies of our forest trees, the fisherman is un- 
derstandably concerned about the effea of DDT upon his 
favorite sport. 

The toxicity of DDT to fish has not been studied as 
thoroughly as has been the toxicity toward warm-blooded 
animals, but experiments that have been carried out indicate 
that fish and cold-blooded animals, such as frogs, snakes, 
salamanders, and crayfish, are killed by quantities of DDT 
which wouldn't even make a warm-blooded animal sick. 

From a practical point of view, this means that waters 
containing fish should not be treated with too high doses of 
DDT. One-half to one pound of DDT per acre of pond or 
stream will kill lots of fish, and will destroy an even higher 
percentage of the aquatic insects upon which the fish feed. 
Therefore, it is a good idea to keep DDT out of the home of 
the fish, except where it is applied for mosquito control and 
the concentrati on is kept very low. 

It s a Bird! 

Birds, unlike fish, can tolerate appreciable amounts of 
DDT without turning up their toes. In faa, birds react to- 
ward DDT in about the same manner as rats, rabbits, sheep, 
and dogs. A toxic dose of DDT is about the same per unit 
of weight for animals with feathers as it is for animals with 

When large forest areas were first treated with DDT for 

62 DDT— Killer of Killers 

the control of such undesirable insect citizens as the spruce 
budworm, gypsy moth, hemlock looper, pine tip moth, spittle 
bug, pine sawfly, and white pine weevil, our nimble nimrods 
and girl-scout leaders joined their brother nature-lovers, the 
fishermen, in expressing fears that the lilting sound of the 
chickadee as well as the drumming of the partridge would be 
stilled forever. This fear, like many others relating to DDT, 
was entirely unfounded. Extensive tests in which forest 
areas were treated by airplane with as much as 5 pounds of 
DDT per acre revealed very few dead birds, although the 
bird population did show a marked reduction a few days 
after the treatment, presumably because the insects — food 
for the birds — had been killed off, and our feathered friends 
had to seek elsewhere for their daily bread. But insects soon 
moved in to repopulate the treated areas, and with them re- 
turned the birds. 

But 5 pounds per acre is much more than is needed. 
When from % to 1 pound of DDT per acre is used — and 
this is all that is needed to control the forest insect pests — 
many insects, particularly of the harmless or beneficial types, 

; still remain alive, and the feathered and furry inhabitants of 

*^ the woods are seemingly unaffeaed. 

The Kriler of Kiriers at Work 

Insecticides are of three different types: respiratory poi- 
sons, stomach poisons, and contact poisons. The naphtha- 
lene used for moth balls is an example of the first type. Such 
poisons are very volatile, that Is, they evaporate rapidly. This 
is a disadvantage, for it shortens the effective life of the 
produa after it has been applied. Furthermore, in high con- 
centrations the respiratory poisons repel inseas and thus drive 

Not Too Hot To Handle 63 

them away to carry out their depredations elsewhere. Thus, 
stomach and contact poisons are of greater importance than 
the other type. 

Let's go out into the garden for a few minutes and 
watch the inseas at work on the potato plants, the cucumbers, 
and the cabbage. If your garden is like the garden of most 
green-thumb enthusiasts, you will have no difficulty in find- 
ing portions of leaves, and even whole leaves, missing, where 
yesterday all were intaa. Now step closer, but don't disturb 
the handsomely-striped little beggar who is unconcernedly 
going about his business. See how fast that hole in the leaf 
gets bigger as he works around the edge? A little arsenic 
would fix him. Let's dust a little or spray some over the 
leaves of our once lovely potato plants. Then, when he and 
his brothers and sisters take their next meal they will eat the 
arsenic along with the leaves and get a fatal stomachache. 

But this black monster over here with the wide-spread- 
ing antennas would have to be handled in a different man- 
ner. Unlike his gaily-colored pal of the potato vines, he ob- 
tains his meal by the soda-straw technique. That long gad- 
get on the front of him is a tube which he sticks right through 
the surface of the leaf in order to suck out the sap in the in- 
terior. A stomach poison would be no good against him 
for it would never reach his stomach. His feeding tube 
would merely penetrate the film of poison on the leaf as he 
searched for pay dirt lower down. In order to hasten the 
end of this guy — literally a little sucker — we must use either 
a respiratory poison or a contact poison. Let's try the lat- 
ter — perhaps some rotenone. We'll spray some on the 
leaves, and as our black friend wanders around looking for a 
nice place to get a meal, his legs will pick up some of the 

64 DDT— Killer of Killers 

poison and Mr. Bug will soon find his equilibrium seriously 

Thus, in order to fight the two kinds of insects, the eat- 
ers and the suckers, we need two kinds of poisons: stomach 
and contact poisons. But think how much simpler it would 
be if we could use one poison that killed both types of in- 
sects. And, we can! For DDT is both a stomach and a 
contact poison. Just think what that means? One sub- 
stance that does the work of two! Truly remarkable, and 
just how remarkable is revealed by the fact that of over 3,000 
synthetic insecticides tested by the U. S. Department of Agri- 
culture, only two — DDT and sodium fluoride — were found 
to have this dual-action property. 

DDT Jif-ters 

Insects, like animals, are literally bundles of nerves. 
Since these nerves control all actions of the body, an injury 
to the nervous system can have very tragic consequences. 
Thousands of people will never walk again because their 
spinal cords were injured — a fact momentarily brought to 
the attention of the world as a result of General Patton's 
fatal accident. 

Insects and animals given a toxic dose of DDT soon de- 
velop tremors and then violent spasms. Watch a fly that 
has come in contaa with DDT? See how he flies around 
like mad for a little while, and then staggers around as though 
drunk before he finally turns over and calls it a day? It is 
easy to see that his nervous breakdown is the real thing, and 
not of the type that bored wives indulge in when they suspect 
that hubby is engaging in extra-curricular activities. 

But how can dragging a foot or the tip of a wing through 


Not Too Hot To Handle 65 

a little DDT bring about this desirable — from man's point of 
view — result? Look at a fly or mosquito and what do you ^ 
see? A number of legs, a proboscis, and various tentacles, I 
or sense organs. All of these members are provided with ! 
nerves. The feet are particularly important for they are the 
organs of taste. Having "tongues" in their feet is certainly 
very unfortunate for the inseas^ for tasting DDT is not to be 

But to go on with the story: Our insect steps into some 
DDT; and then what happens? The poison dissolves in 
the nerve substance and gradually works its way up the leg 
to the vital nerve centers, causing a progressive case of jit- 
ters as it migrates. This process, however, takes time. Many 
people, misunderstanding the action of DDT, have been dis- 
appointed with the results that they obtained. They put 
some solution in a spray gun, tiptoe carefully up to a fly, 
and let him have it. And the fly, very perversely, flies away. 
Ten minutes later the fly is still around, somewhat unsteady 
perhaps, but still alive. So our big-game hunter, with a 
shrug of disgust, throws his spray gun away and cries out in a 
loud voice, "DDT is no good!" But the fly is doomed. And 
if our hunter watches long enough, he will see a final kick, a 
shudder, and then peace, as the fly stretches out on his back, 
with his legs motionless in the air. 

A contact poison does not work instantaneously — youl 
must give it time. We can show that easily. Let's take two '' 
flies and put some DDT on one foot of each. A few min- 
utes later let's cut off the treated leg of one of the flies, leav- 
ing the other fly intact. The amputated leg will show pro- ] 
nounced tremors and violent spasms for quite some time; bat ; 
the fly who lost his leg will live. This shows conclusively 
that it takes an appreciable time for the poison to travel up 

66 DDT — Killer of Killers 

the leg, and ii the leg is severed before the poison has reached 
the insea's body, the fly will live. Of course, the other fly 
who does not undergo the amputation will soon join his an- 

It has been mentioned previously that single doses ^f 
Ko gram of DDT per kilogram of body weight are harm- 
^less. To produce symptoms of heavy poisoning or death re- 
quires a minimum of from 0.15 to 2 grams per kilogram, de- 
pending upon the individual as well as on the species. These 
figures, however, refer only to warm-blooded animals. Per 
kilogram of weight, it takes only from 0.0006 to 0.002 grams 
of DDT to kill an insea. And since it takes thousands of 
flies to equal a kilogram of weight, the amount of DDT nec- 
essary to kill a single fly must be considerably less than a 
billioneth of a gram. And that is why DDT is such a good 
residual inseaicide. 

Flies can pick up fatal doses by walking over surfaces 
covered with an almost unbelievably thin film of DDT. In 
an experiment carried out by Geigy, a box made of wooden 
frames and glass panels was sprayed with a %o % solution of 
DDT in acetone, and after the solvent had evaporated, each 
pane of glass was wiped 200 times with a woolen cloth. Flies 
were then introduced into the box, and they picked up enough 
DDT by walking over the polished glass to kill them within 
a few hours. Obviously, when residual sprays are applied to 
wooden or plastered walls, much greater amounts must be 
used because a lot of the material penetrates into the pores 
and does not remain on the surface where insects can get in 
touch with it. 

Chapter Four 


DDT Formulations 

From Laboratory to You 

xTlCCORDING to the old words of wisdom, 
everybody talks about the weather but nobody does anything 
about it. Likewise, everybody talks about DDT but few 
know what they are talking about. They spray with DDT 
and they sprinkle DDT powder around, without realizing the 
fact — which they could readily determine by reading the la- 
bel — that their sprays or powders are formulations of which 
DDT is only one of the ingredients, and a minor one at that 
in terms of weight percentage. Pure DDT is never used as 
an insecticide: it is always incorporated with other substances, 
either aaive or inert, in order to give the best produa for the 
particular job. And if you use the wrong formulation for 
your particular job, don't blame the DDT if you don't get 
satisfactory results. 

It is true that when DDT formulations were first 
dropped into the outstretched arms of a waiting public, some 
unscrupulous companies, taking advantage of the tremendous 
publicity that DDT had received, duped the citizens by put- 
ting out products with insufficient DDT to do the jobs 
claimed. But the U. S. Government as well as the various 
states have names for such operators and have clamped 
down on their aaivities. Since all inseaicides sold must 


68 DDT — Killer of Killers 

bear labels approved by the U. S. Department of Agriculture 
or the Agricultural Departments of the states, one can feel 
certain today that the claims for a particular product are hon- 
est ones. Therefore, the best advice is: read the label be- 
fore you buy, and read it carefully, j&ne type and all. 

Shop around in your favorite stores and see how many 
different types of DDT formulations you can find. If you 
study carefully, you will find that they fall into the follow- 
ing classifications: (1) Household sprays, which are solu- 
tions of DDT and perhaps other insect killers in petroleum 
solvents, usually deodorized kerosene. These are of two 
types: residual sprays, with DDT contents of 5 or 6%; and 
space sprays, containing about /4 to 1 % DDT. These are 
the common sprays used against the fly, mosquito, and other 
pests that like to share man's abode. (2) Aerosols. These 
are little metal bombs, usually containing 3 % DDT and 2 % 
pyrethrum extract dissolved in a very volatile solvent. When 
the valve of the bomb is opened, an extremely fine spray mist 
shoots out and kills all insects — principally flies and mosqui- 
toes — that it hits. ( 3 ) Household powders, usually made 
up of 10 % DDT and the rest talc, pyrophyllite, or some other 
inert extender. These powders, which are so effective against 
bedbugs, fleas, ants, and other crawling insects, may also 
contain pyrethrum or other lethal agents. (4) Emulsi- 
fiahle solutions. These are concentrated solutions of 25 or 
30% DDT in organic solvents and dispersing agents. For 
use, they are mixed with water to prepare emulsions, of about 
2% or 5 % DDT, for the control of flies and other insects in 
barns, poultry houses, and other outbuildings, and on cattle, 
horses, and other farm animals. They are also used for the 
control of various insea pests on agricultural crops, forest and 
shade trees, and other vegetation. ( 5 ) Wettahle powders, 

DDT Formulations 69 

containing up to 50% DDT and the rest inert ingredients, 
used as dispersions in water for the same purposes as DDT 
emulsions. (6) Agricultural dusts, containing usually 
from 1 to 5 % DDT, for direct application to field crops for 
the control of various insect pests. (7) Paints, usually 
with about 5 or 6% DDT incorporated in a synthetic-resin 
binder, principally for interior purposes where residual insea- 
killing powder is desired. 

Sprays and Sprays 

When the housewife goes into a store and asks for some 
DDT, the clerk hands her a bottle of stuff with the letters 
DDT in large type. The DDT content may he 5% or less, 
so the good woman should stop a moment and think be- 
fore saying those words that every clerk likes to hear: "I'll 
take it. How much is it?" If she wants something that 
she can apply to the walls of the dining room so that the flies 
that light there over the next six months will die, she had 
better make sure that it says 5 % in front of the letters DDT. 
But if she merely wants to kill the flies that happen to be 
around at the moment she sprays, she will find that a con- 
siderably lower concentration of DDT will do the trick. 

You see, fly sprays are of two types: space sprays and 
residual sprays. Space sprays have been in use for many 
years, and those exciting words, "Quick, Henry, the Flit," 
have been heard from one end of the land to the other — 
much to the profit of the manuf aaurer. When using a space 
spray you merely aim your gun in the general direaion of the 
insects and hope that some of the misty particles hit each pest. 
Any insect who escapes the spray is safe, at least until the 
next time you let go with your ammunition. The older space 

70 DDT — ^Killer of Killers 

sprays were prepared by making a kerosene solution of pyre- 
thrum or an organic thioq^anate. Pyrethrum is a naturally- 
occurring poison found in the blossoms of a daisy-like plant 
grown in British East Africa, Belgian Congo, Japan, and 
Brazil. The thiocyanates are synthetic chemicals sold under 
the trade names of Lethane and Thanite. Pyrethrum is rath- 
er unstable: when exposed to light or to the air it soon de- 
composes. Thus, it has no lasting action. Pyrethrum, how- 
ever, is a good killer, and because it is praaically odorless, \t 
is much in demand for fly sprays. 

The thiocyanates are also effective killers, but they must 
be used in much higher concentrations than pyrethrum. Dur- 
ing the war when pyrethrum became scarce, practically all 
household insect sprays were made with these synthetics. The 
thiocyanates are more stable to light and oxidation than is py- 
rethrum, but even they have no residual aaion. In other 
words, a wall sprayed with a thiocyanate solution would not 
continue to kill insects. One disadvantage of the thiocya- 
nates is that they have an unpleasant and persistent odor 
which lingers on for a long time in an area where the spray 
has been used. 

Both pyrethrum and the thiocyanates, in addition to be- 
ing good killers, have rapid knockdown properties. This is 
important. When you use a space spray you want to get 
rid of the insects in a hurry. It is no consolation to know 
that they will be dead in a few hours. You want to keep 
them out of your soup now. That's where rapid knockdown 
comes in. The insects drop to the floor within a few min- 
utes, although they may continue to live for another hour 
or so. 

DDT Formulations 71 

Grade AA 

Perhaps you've noticed on your bottle of insect spray 
the statement that it is a Grade AA inseaicide. You prob- 
ably didn't give it another thought, resting content with a 
feeling of security that anything marked AA must be tops. 
Would you like to know a little more about the meaning of 
these letters? Well, here goes! 

When you go into a store to buy a bottle of insecticide, 
you can't tell by feeling, tasting, or smelling the contents of 
the beautifully<olored containers which one is good or which 
one is bad, or how much better one is than another. Of 
course, this is true of most things you buy. But after you 
buy something and try it out, you soon find out whether or 
not you were a sucker for making the purchase. And if you 
come to the conclusion that you didn't get your money's 
worth, you certainly won't buy that particular brand of article 
again. Manufacturers know this as well as consumers. They 
know that to keep your business they must give honest value 
and make no false claims. Perhaps this is the best type of 
control for industry — control based only on the seller-pur- 
chaser relationship, without Government interference. Any- 
way, that's what lots of people believe, although lots of others 
take the attitude that the public can't manage its own affairs 
and has to have the Government aa as its guardian. For 
further light on this interesting subject, read again the volu- 
minous arguments, pro and con, over O.P.A. 

Without delving further into the philosophy of price 

and quality regulation, we will merely state that insecticide 

manufacturers felt, for a long time, that it would be a good 

idea for the industry to voluntarily agree on certain standards 

of performance for household insecticides of the space-spray 

72 DDT — Killer of Killers 

type. With standards of performance set up, the various 
manufacturers would have a common basis for comparing 
the qualities of their different products, and each manufactu- 
rer who desired could then indicate on his labels how his 
insecticide stacked up with the others. 

On September 20, 1937, the National Association of 
Insecticide and Disinfectant Manufacturers, Inc. proposed 
the establishment of a commercial standard for household in- 
secticides of the liquid-spray type; and the standard was later 
accepted and approved for promulgation by the U. S. Depart- 
ment of Commerce, through the National Bureau of Stand- 
ards. This standard — known as G)mmercial Standard 
CS72-38 — became effeaive on June 10, 1938. If you are 
interested, the Superintendent of Documents, Washington, 
D. C, will sell you a copy for 5 cents. 

An inseaicide that meets the requirements of the stand- 
ard must be harmless to man and warm-blooded household 
animals when used as direaed; it must not stain household 
furnishings, wall paper, etc.; it must not corrode metals; and 
it must have no objectionable odor. But the most important 
of the specifications deals with performance. And the only 
way you can tell what an inseaicide will do is to try it out 
on insects. 

For determining the killing power of a liquid insecti- 
cide, the Peet-Grady method has been accepted as the stand- 
ard. In this method, approximately 100 houseflies, not 
less than 3 nor more than 5 days old, are placed inside of a 
test chamber, which is a 6-foot cube, constructed of wood or 
metal, and lined so that the inner surface is smooth, relative- 
ly nonporous, and free of cracks, projections, etc. The cham- 
ber is provided with a large, tight-fitting door, windows for 

DDT Formulations 73 

observation and lighting, and various openings for admitting 
insects and insecticide, and for ventilation after the test. 

After the flies are in place, 12 milliliters (about % 02.) 
of the insecticide are injected into the chamber with a special- 
type atomizer. Ten mi nutes later, the ventilating fan is 
turned on, the door is then opened, and the number of flies 
clinging to the ceiling and walls, together with any that are 
still flying, are counted. These are considered to be unaf- 
fected by the inseaicide. The flies which have fallen to the 
floor are transferred to observation cages and are examined 
at the end of 24 hours to determine the number which are 
dead. Any flies that have revived during this period are also 
considered as unaffeaed by the inseaicide. The percentage 
of the original flies which are found dead at the end of 24 
hours is known as the percentage kill. 

Each time an insecticide is tested, duplicate runs are 
made — one with the insecticide being tested and the other 
with the official test insecticide of the National Association 
of Insecticide and Disinfectant Manufacturers, Inc. If the in- 
secticide being tested has a "kill" of from 5 % less to 5 % 
more than that of the official test insecticide, it is given the 
designation Grade B. If its "kill" is from 6 to 15 % great- J 
er, it is classified as Grade A. And if its "kill" is 16% or jf 
more above that of the standard, it carries the highest rat ing p 
of all — Grade AA. 

Now you know what the words Grade AA on an in- 
seaicide label mean. But, you won't find the letters AA, 
A, or even B on all household sprays. This does not neces- 
sarily mean that the insecticide is of poor quality, for you 
must remember that acceptance of Commercial Standard 
CS72-38 is not compulsory, and some manufacturers just 
haven't bothered with it. However, most inseaicide manu- 

74 DDT— Killer of Killers 

facturers and distributors have agreed to accept this standard, 
and it probably won't be very long before every bottle of 
household space spray you buy will bear the sign of distinc- 
tion — Grade AA. 

100% Active 

The bottle of insea spray that you buy probably also 
carries the words: 100% Active Ingredients. Since the ma- 
jor part of the material in the bottle is kerosene, this can 
only mean that kerosene itself is an insect killer. That is 
correal Petroleum solvents — ^gasoline, kerosene, naphtha, 
fuel oil, etc. — as well as lots of other organic solvents do have 
lethal properties as far as insects are concerned. When your 
suit comes back from the dry cleaner, it is hee from moth 
larvae, for they cannot survive their naphtha bath. Obvi- 
ously, kerosene in itself is not sufficiently satisf aaory for use 
alone as a fly spray, for if it were no one would bother to put 
in some pyrethrum, thiocyanates, or DDT. Nevertheless, 
the kerosene does contribute to the killing power of the 



Oil to You 

Kerosene, or as some people erroneously call it, coal 
oil, is probably known to you as the material that was used 
to furnish the light of the world in the days before Thomas 
Edison found out that a piece of charred cotton inside of an 
evacuated glass bulb could transform elearicity into light. 
Yet, even today the kerosene lamp is a familiar sight in many 
places where the elearic wires have yet to reach. Tech- 
nically, kerosene is just a petroleum fraaion that boils over 
the temperature range of about 400 to 500°F. 


Fig. 11. Garbage Cans Sprayed Inside and Outside with 5% 
DDT Will Not be Breeding Grounds for Flies. 

(Courtesy of Hercules Powder Co.) 




Fig. 12. A Flick of the Valve and the Death-Dealing DDT 

Mist from This Aerosol Bomb Will Spell the Doom of Every 

Insect Flying or Hiding in This Room, 

(Courtesy of Hercules Powder Co.) 


Fig. 13. Sergeant Edward J. Haladay Releases an Aerosol 

Mist to Kill Any Insects That Are Lurking in the 

Barracks Where His Company Sleeps. 

(Courtesy of U. S. Dept. of Agriculture. Photo by Knell) 


Fig. 14. Nurse Willis Craft Sprays a Bed at the Arlington. 

Va. County Hospital with 5% DDT to Eliminate the 

Bedbug Problem. 

(Courtesy of U. S. Dept. of Agriculture. Photo by Madeleine Osborne) 


DDT Formulations 79 

Kerosene is a good material for household inseaicides 
because it doesn't evaporate too rapidly, and thus carries the 
poisons where they will do the most good. In addition, 
there is much less fire hazard with kerosene than there would 
be with the much-more-volatile gasoline, although you must 
keep kerosene away from open flames, as many people have 
found out to their sorrow when they poured some kerosene 
into the old wood stove, not noticing that there was still 
some fire or hot coals present. 

The ordinary kerosene or No. 2 fuel oil that your 
dealer can supply you with is perfealy all right for making 
an insect spray, particularly for use in barns and chicken 
coops, but its irritating odor is rather objectionable around 
the house. For that reason, most household insecticides are 
made with kerosene that has been treated to remove the 
odoriferous constituents. Incidentally, deodorizing is ap- 
parently an expensive process; at least the deodorized product 
costs about three times as much as the produa you burn in 
your lantern. To top it all off, manufacturers, to cover up 
the odors of their insecticides, add small amounts of per- 
fumes to "make it stink pretty." 

Why DDT in Space Sprays? 

In spite of the faa that pyrethrum and the thiocyanates 
are rather good insect killers, they can't compare with DDT. 
A Viofo solution of DDT will kill a higher percentage of 
insects than will much higher quantities of these other kill- 
ers, and at a much lower cost. But DDT, in spite of its 
marvelous killing powers, is slow acting: it does not have the 
desirable high knockdown characteristics of the other in- 
secticides. Therefore, a kerosene solution of DDT alone 

80 DDT— Killer of Killers 

does not make a good space spray: it will kill all the insects 
at your party, but not until after the guests have gone home. 
The logical answer? Use enough DDT to give prac- 
tically 100% kill. This does not require a high concentra- 
tion — perhaps /4 to 1 %. And then add enough pyrethrum 
or one of the thiocyanates to give practically 100% knock- 
down. Since you are not depending upon these latter ma- 
terials for kill but only for knockdown, you need much small- 
er concentrations than you would if you had to depend upon 
these agents for both knockdown and kill. 

The Killing Mist 

During the war, about sixteen million little bombs were 
distributed to our fighting men. These bombs contained no 
high explosive, but they spelled death to many a lurking 
enemy — Anopheles, the malaria-bearing mosquito. 

On every Pacific island that formed a stepping stone to 
Japan, our soldiers, sailors, and marines found that mosquitoes 
swarmed in the jungles. It wasn't so bad during the day, 
for mosquitoes shun the sun. But at night, when all was 
dark and still, they searched out the sleeping forms of men 
and had their midnight snacks. Mosquito netting on bar- 
racks windows and across the end of tents kept out the tiny 
marauders at night. But what about the mosquitoes that 
managed to get in during the day and went into hiding, wait- 
ing until it got dark and the men were asleep so that they 
could slip out and attack without interference? 

That's where these little bombs — the aerosol bombs- 
came in so handy. A flick of the valve, and within a few 
seconds the room or tent was filled with a mist of DDT and 
pyrethrum; and the mosquitoes dropped dead in mid air, or 

DDT Formulations 81 

if they happened to be hiding at the time, the mist floated 
in on them and spoiled their plans for an evening meal. 

Some years ago the late Thomas Midgley, of General 
Motors Corp., developed a new refrigerant for use in domes- 
tic and commercial refrigerators and in air-conditioning units. 
This substance — dichlorodifluoromethane — known as Freon- 
12, is a non-toxic gas at ordinary temperatures. To liquefy 
it at atmospheric pressure, you must cool it to about 22 deg. 
F. below zero. To liquefy it at room temperature, you must 
put it under considerable pressure. To make an aerosol 
bomb, all you have to do is dissolve 3 % DDT and 2 % py- 
rethrum extract in Freon-12 under pressure and charge the 
mixture into a metal container which is strong enough to 
withstand the pressure. When the valve is opened, the 
mixture under pressure rushes out at high velocity through a 
very small opening. This breaks the stream up into an ex- 
ceedingly fine mist — the particles of which are very much 
smaller than the particles from an ordinary spray gun. 
Furthermore, with the release of the pressure, the solvent 
evaporates almost instantaneously, leaving the minute 
particles of DDT and pyrethrum suspended in the air. Be- 
cause they are so fine, these particles do not readily settle out 
of the air; instead, they are carried around by the air cur- 
rents, reaching practically all parts of the room. 

Although developed primarily for killing mosquitoes in 
army and navy barracks and tents, the aerosol bomb is equal- 
ly effective on other household insects, such as flies, sandflies, 
and moths in the flying stage. Their convenience of use and 
the rapid effectiveness of aerosols as space sprays led to con- 
siderable civilian demand for the bombs, and it was an easy 
matter for the manufacturers to turn from wartime to peace- 
time production. 

82 DDT— Killer of Killers 

Aerosols are the most expensive of the DDT formula- 
tions, but since only a small amount is needed to free a room 
of insects — a 1 -pound bomb is enough for about 25,000 
cubic feet of room space — the actual cost for treating the 
rooms of a house is not excessive. 

It is interesting to note that Dr. Midgley, who unin- 
tentionally made an important contribution to the field of in- 
secticides, was himself a viaim of poliomyelitis — a disease he 
may have contracted through the medium of a fly. 

Long- Lived Action 

Without belittling the ordinary space spray or the aero- 
sol bomb, we must admit that the one thing about DDT that 
attracted and held the attention of everyone was the fact that, 
when properly prepared and applied, a single application of a 
DDT formulation continues to kill insects for weeks, and 
even months. This is a unique property not possessed by 
any other insecticide for household use. Whenever one 
thought of DDT, he did so in terms of this residual action. 
As just another ingredient of a space spray, DDT was of little 
interest, for the sprays that one had been used to buying did 
a fairly good job. Yet, many of the insect sprays that were 
first sold to the public during the latter part of 1945 did not 
have residual action, for the quantity of DDT was too small. 

To be a residual spray, the solution should contain at 
least 5% DDT. And it should be applied at the rate of 
about one quart for each 250 sq. ft. of surface, if long-lasting 
killing is desired with a single application. 

This does not mean that solutions with less than 5 % 
DDT have no residual action. They do! But remember 
that you can only spray so much liquid on the wall without 

DDT Formulations 83 

having it run. If your spray solution contains less than 5 % 
DDT, the deposit left after evaporation of the solvent will be 
correspondingly thinner. Of course, you can re-spray a gW^n. 
surface a number of times, permitting the solvent to evap- 
orate between sprayings. In this way you can build up a 
good deposit of DDT on the surface. But, five sprayings 
with a 1 % DDT solution have proved less effective than a 
single application of a 5 % spray. And anyway, why make a 
lot of extra work for yourself by using a 1 or 2 % DDT spray 
when a 5 % spray will do the job with one application. 

But just because you buy a 5 % DDT spray don't get 
the idea that your problems are over. It is up to you to see 
that it is properly applied. Too many people put the stuff 
in their spray guns, take three squirts at the wall, and expect 
their house to be free from insects all summer. And when 
they find the insea population thriving, they blame the DDT 
and not themselves. 

You see, a residual spray works like this: You spray 
the walls, lamp cords, screen door, and other places where 
inseas light, and when the solvent evaporates the DDT 
crystallizes out and remains on the surface. When a fly or 
a mosquito rests on or walks across such a treated surface, he 
picks up some DDT and dies, usually in one to three hours, 
with tremors and spasms. 

Residual sprays do not need knockdown agents, al- 
though it would be nice if something could be added along 
with the DDT so that the insects dropped dead as soon as they 
hit the wall. Pyrethrum and the thiocyanates are not of 
much help because they do not remain effective for very long. 
Nevertheless, many residual sprays now contain pyrethrum 
or thiocyanates — about 1 % of pyrethrum extraa or 2 to 3 % 
of the thiocyanates. This is a good idea, for then the spray, 

84 DDT— Killer of Killers 

in addition to being a residual spray, can also be used as a 
rapid-knockdown, high-kill space spray. Thus, a single 
spray can take the place of two. 

Although residual sprays are most commonly used for 
controlling flies and other insects on the walls of homes and 
barns, they are also very effective against bedbugs and clothes 
moths. Three fluid ounces of a 5 % DDT-kerosene mixture 
properly applied to a full-sized bed will keep it free from 
bedbugs for six months. Operators of hotels and rooming 
houses will appreciate the value of this. They also know 
that a bedbug spray should be as free from residual odor as 
possible so as not to advertise to the guest that the bed he is 
to occupy was once the dwelling place of repulsive little crea- 

The 5 % DDT-kerosene solution is also a good mothi- 
cide. But because kerosene takes a rather long time to evap- 
orate, there is some advantage in using the much-more-vola- 
tile naphtha in place of kerosene. The fire hazard is some- 
what greater with naphtha solutions, but one should have 
no difficulty if he follows the same rules of caution that he 
does when treating his clothes with cleaner's naphtha. In- 
cidentally, if your good wool suit is treated with DDT, it will 
remain free from moths for at least several months, unless 
the deposit is removed by dry cleaning. 

Powdered Death 

Does your dog have fleas? Or do you have lice in your 
pants? Don't use the spray gun! The spray would kill 
these insects all right, but there is a possibility that some of 
the poison might be absorbed through your dog's hide or your 
tender skin. Take a powder — literally — a DDT powder, 

DDT Formulations 85 

and sprinkle it in your pooch's fur or in your underwear. A 
10% DDT powder is what you want — the same material 
that proved so effective in stopping the typhus epidemic in 

These powders are made by grinding DDT with an in- 
ert ingredient, usually pyrophyllite or talc. The powder 
flows easily and adheres well. Like the residue left from a 
5 % DDT spray, the powder has residual action, retaining 
its effectiveness for months. 

About 1% oz. of the powder sprinkled around on the 
mattress, springs, and joints of a full-sized bed will keep it 
free from man's nocturnal companions — the bedbugs — for at 
least six months. Sprinkled around the hiding places of 
cockroaches, the powder will eventually rid the premises of 
these pests, although it takes about a week before you can 
see the results. Similarly with ants: sprinkle the cupboard, 
baseboards, under the sink, and other places where these 
little insects migrate. Of course, be sure you don't get the 
powder on food, for you want to kill the inseas, not your- 
self. But don't worry about getting it on your skin. It 
won't hurt you. And it won't hurt your dog to have a good 
deposit of DDT on his hide either. But don't use it on your 
cat, for he — or is it a she? — likes to lick himself to keep his 
fur nice and clean. Licking up some DDT probably wouldn't 
kill him but it might make him sick. However, you can 
control his fleas by sprinkling the powder around the place 
where he sleeps. 

Milky White 

It is unfortunate that DDT is not soluble in water. If 
it were, it would be much easier to use for many purposes. 

86 DDT— Killer of Killers 

But, no use speculating upon something that can't be. If 
we can't dissolve it in water, we can at least disperse it in 
water, and that is some help. We can make two types of 
dispersions: We can mix up a dry DDT powder with water, 
or we can dissolve the DDT in some organic solvent to make 
a concentrated, 25 or 30% solution, and then we can mix 
the solution with water. We'll talk about the first type of 
dispersion, known as a suspension, in a few minutes. But 
first, let's take up the second type, known as an emulsion. 
This is a dispersion of one liquid in another. 

An emulsion has two phases: a dispersed phase (in this 
case, a solution of DDT in a solvent) and the dispersion 
medium (in this case, water). We can't use kerosene or 
fuel oil as the solvent for DDT in the preparation of emul- 
sions because the DDT is not soluble enough in these sol- 
vents. To get 25 or 30% DDT in solution, a material like 
xylene, a coal-tar hydrocarbon, must be used. Furthermore, 
we must use a third substance, known as an emulsifying 
agent, in order to give a product which is relatively stable. 
You know the old saying that "oil and water don't mix." 
This is not strictly correct. It is true that oil will not dis- 
solve in water, but under the proper conditions you can get a 
mixture that is so uniform that it looks like a single sub- 
stance. You can try this yourself: Shake up some water 
and kerosene together. See how milky it looks? But now 
let it stand without shaking. Notice how the little particles 
of kerosene coalesce and rise to the top? All you have left 
is a layer of kerosene on top of a layer of water. 

Now add a little soap and shake up the water and kero- 
sene again. See how much longer it takes for the kerosene 
to separate out? The soap is the emulsifying agent. Once 
upon a time soap was about the only emulsifying agent we 

DDT Formulations 87 

had, but today there are a wide variety of synthetic substances 
that are much more effective than soap. These materials 
come on the market under a variety of trade names, a few of 
which are Emulphor, Chovis, Mulag, Tween, and Tegin. 

The quantity of emulsifying agent needed is not very 
great. For example, a good 30% DDT concentrate for 
emulsion purposes can be made by dissolving 30 parts by 
weight of DDT and 4 parts of an emulsifying agent in 66 
parts of xylene. 

Since these concentrates are made with organic solvents 
such as xylene, they are inflammable, just like the ordinary 
5 % DDT-kerosene solution. Furthermore, the concentrate 
must never be used as such on animals or plants. Not only 
is the DDT concentration too great for direa use, but the 
solvent itself might cause damage. 

To make a 5 % DDT emulsion from a 30 % concen- 
trate, you simply stir one part of the concentrate into 5 parts 
of water. Because of the large amount of water in propor- 
tion to solvent, the emulsion is nonflammable. Thus, it 
makes a nice product to apply to the walls of barns and other 
buildings as a residual spray for the control of flies. How- 
ever, it should not be used in homes because the water would 
streak and stain your pretty wall paper. 

Also, because of the low concentration of solvent in the 
finished emulsion, emulsion sprays can be used on animals 
as well as on plants. But for use on plants, you will want to 
dilute the concentrate to make a spray with only about % or 
1 % DDT. So follow the direaions on the bottle before 
going after the bugs. 

Powders That- Wet 

Well, if you can dissolve DDT in a solvent and then 

88 DDT— Killer of Killers 

disperse it in water, why not forget about the solvent and just 
disperse the DDT directly in water? This would have lots 
of advantages — if it could be done. But it can't! The ^ 

crystals of DDT are somewhat waxy; they stick together and | 

form lumps. You can't grind the DDT to a fine powder, 
and even if you could it would not stay that way. But you 
can grind DDT with an inert flaky material such as talc, 
pyrophyllite, or clay and get a very uniform product con- 
taining up to 50% DDT. And while you are grinding the 
DDT and the inert material together, add small quantities of 
wetting agents and sticking agents. Then when you mix 
the powder with water, it will disperse readily, and when you 
spray it on your cows or rose bushes the powder that is left 
after the evaporation of the water will stay put and not blow 
away with the gentlest zephyr. 

One pound of a 50% wettable powder to about 5 gal- 
lons of water makes a good residual spray for the control of 
flies in barns and on cattle, and about 30 pounds per 1,000 
gallons of water is fine for dipping sheep and hogs for the 
control of ticks and lice. One disadvantage of the use of 
wettable-powder sprays is that they leave a white deposit on 
the walls, and this limits the use of such a spray to barns and 
similar buildings. 

For agricultural purposes, the powders are mixed with 
water, usually in the ratio of about 1 to 2 pounds of 50% 
DDT powder per 100 gallons of water. Sulfur, Bordeaux 
mixture, organic fungicides, and other materials may be in- 
corporated in the spray to make an all-round inseaicide and 

Dust the Plants 

Some farmers, as well as amateur gardeners, prefer to 

DDT Formulations 89 

dust their plants rather than spray them. Such individuals 
will find powders specially prepared for them. These pow- 
ders contain, most commonly, either 3 or 5% DDT, but 
mixtures of other concentrations can be purchased. These 
powders can also be obtained with copper or sulfur, or with 
other fungicides and insecticides; or the farmer or gardener 
may purchase the straight DDT powder and mix it with his 
favorite ingredients. 

Save the Surface 

If spraying a solution of DDT on your walls will leave 
a deposit that will kill insects for months, why not mix DDT 
with the paint used for the interior of houses and get a finish 
that will kill insects as long as the paint film lasts? Many 
imaginative individuals came up with this logical-sounding 
idea, and many exaggerated claims have been made. Now 
we can sift fact from fiction. 

The ordinary oil paints and varnishes don't seem to be 
any too good for mixing with DDT. The DDT mixes with 
the paint all right, but the dried paint film doesn't have very 
good killing properties. It seems that the dried oil film traps 
the DDT and keeps it from coming in contact with the in- 
seas. That's one way to save DDT — just like covering the 
ice in the refrigerator with newspapers so it won't melt: You 
save ice but don't get very good refrigeration. If saving 
DDT is the object, better keep it in the can instead of lock- 
ing it up in a paint film. 

Some of the oil-bound water paints and synthetic resin 
finishes, however, seem to give good results. For some of 
these products claims have been made that they retain their 
killing action for over several months. To be effective, the 

90 DDT — ^Killer of Killers 

binders must permit the DDT to migrate to the surface of 
the film where the insects can get in touch with it. Since the 
DDT on the surface will gradually vaporize and be lost, 
other DDT must take its place if the paint film is to retain 
its effectiveness. 

One product of this type is sold under the trade name 
of Pestroy. It is a colorless, synthetic-resin liquid with 6 % 
DDT. It can be brushed on screens, ceilings, stairs, or other 
surfaces, and dries in a short time to an almost invisible film 
which is lethal to inseas but which will withstand consider- 
able rubbing. The claims for this product are very modest: 
the manufacturer merely states that one application will re- 
main eflPeaive for at least three months inside, and at least a 
month outside. 

Chapter Five 

Common Insect Enemies 

The Lousy Louse 

JLVEMEMBER these immortal words of 
Robert Burns that you were forced to memorize back in the 
days when you were a little schoolboy or schoolgirl? 
"O wad some Power the giftie gk us 
To see oursels as ithers see us! 
It wad frae mony a blunder free us, 

An' foolish notion: 
What airs in dress an' gait wad lea'e us, 
An' ev'n devotion! " 
And what prompted Burns to write these words of wis- 
dom? Nothing but a lowly louse on the bonnet of a well- 
dressed lady who was piously sitting in church, entirely ob- 
livious to the fact that her uncleanliness was to be the in- 
spiration for a famous poem, entitled "To a Louse." This, 
seemingly, was the only louse in history that ever did anyone 
any good. Its countless brothers and sisters are at best 
merely loathsome creatures, and at their worst they are among 
the most deadly of man's innumerable insea enemies. 

When speaking about lice, one must be very careful to 
differentiate between the three types that attack man: the 
body louse Pediculus corporis, the head louse Pediculus cap- 
itis, and the crab, or pubic, louse Phthirius pubis. Of these 
three, the body louse is the most dangerous for it is the prin- 


92 DDT— Killer of Killers 

cipal carrier of a number of diseases, the most serious of which 
is epidemic typhus. 

Fortunately, cleanliness is the enemy of the louse, and 
since about the only people in this country who seem to have 
an almost pathological dread of soap and water are those care- 
free citizens known variously as hoboes, tramps, and bums, it 
is only among this group of individuals that the body louse 
is found to any great extent in the United States. Thus, 
louse-borne diseases are of relatively little importance in this 
country. But in other parts of the world, the situation is 
quite the opposite. Millions of inhabitants of Europe, Asia, 
and Africa live under conditions of filth almost unbelievable 
to an inhabitant of a country where the greatest bulk of radio 
advertising is devoted to the sale of soap. 

An adult body louse is a rather good-sized brute, about 
% inch long, and grayish in color. It emerges from a whit- 
ish egg, or nit, which hatches at body temperature about 8 
days after the egg is laid, and spends about 9 days in the 
nymphal stage, during which it sheds its skin three times as it 
grows to an adult. And if our louse happens to be a female, 
she begins to lay eggs about a day after she emerges as an 
adult, and she may live as long as a month, laying 4 or 5 
eggs each day. 

The body louse makes its home in its host's clothing, 
and it leaves its home several times a day to visit its host's 
skin and acquire nourishment. Sometimes the female lays 
her eggs on the hairs of the body, but usually she deposits 
them in her host's clothing, particularly in the seams and 
folds. And she glues her eggs to the fibers of the cloth. 

Since the body louse does not live on the body but 
rather in the clothing, it is relatively easy to control this un- 
welcome boarder. All stages of the louse are killed by 

Common Insect Enemies 93 

washing the garments in hot water or by dry cleaning. If a 
person changes to clean clothing every week, he will not have 
body lice. 

But, where whole communities live in homes where 
cleanliness is not practiced, where soap is not available, and 
where anyone with a change of clothing is considered a pluto- 
crat, the problem of louse control is a much more difficult 
one. But now with DDT, as results in Naples have shown, 
no individual or community need suffer any longer from the 
dreaded typhus and other louse-borne diseases. A single 
application of 10% DDT powder to all individuals in an in- 
fested community will completely eradicate the lice. One 
ounce of powder applied to the inner surface of undercloth- 
ing and another % to 1 ounce applied to the seams of the 
outer garments will continue to kill lice for months there- 

Whafs That In Your Hair? 

Was little Johnny sent home from school recently with 
a note from the school nurse saying that he must get rid of 
lice before he would be permitted back in school? And did 
you feel deeply mortified at this insult to the cleanliness of 
your home? Don't feel too badly, for it takes more than 
cleanliness to keep away these little fellows. Maybe they 
just preferred Johnny's clean head to the dirty head of his 
schoolmate who brought the lice to school, to distribute un- 
intentionally among all the children. 

But now that the tell-tale nits have been spotted by the 
eagle-eyed nurse, don't get the idea that all you have to do is 
put Johnny under the shower and give him a good shampoo. 
The lice and nits are a little too tough for that: they can sur- 

94 DDT — Killer of Killers 

vive several good shampooings, and you can comb and brush 
his hair all you want, but some of the lice and nits will es- 
cape your most persistent exertions. 

Before we tell you what to do, we feel that you should 
know that the head louse looks just about the same as the 
body louse. In fact, the head louse and the body louse are 
so similar that they can interbreed and raise families of lively 
hybrids. However, you know he is a head louse because he 
is found on the head. It's as simple as all that! But if you 
find a louse on your body he may be either a body louse or a 
crab louse, as you shall learn in a little while. 

Is the head louse just a nuisance, or is he, like his brother 
the body louse, a carrier of disease? For a number of years 
the finger has been pointed at the body louse — "There's the 
carrier of typhus!" All right, he is! But that doesn't mean 
that he is the only carrier. One would certainly suppose 
from the similarity between the body louse and the head louse 
that the latter might also be guilty. And he is! It has been 
shown under experimental conditions that the head louse can 
transmit typhus, and there is plenty of reason to believe that 
he does this under natural conditions. 

After all, the body louse is merely a development of 
the head louse. Primitive races who wear little or no cloth- 
ing have no body lice. Yet, long before they first started to 
wear clothes, our naked ancestors had an abundant supply of 
lice on their heads. With the advent of clothing, some ad- 
venturous members of the head louse family migrated down- 
ward and established themselves in this new environment. 

Just when typhus first appeared on the earth will never 
be known, for it was undoubtedly long before recorded his- 
tory. However, because of the absence of body lice in these 
very early days, it seems likely that head lice were busy 

Fig. 15. This Soldier is Treating the Interior Surfaces of a 

Barrack with DDT Residual Spray to Insure Immunity 

Against Mosquitoes for Several Weeks. 

(Courtesy of U. S. Dept. of Agriculture. Photo hy Madeleine Osborne) 


Fig. 16. A Measured Quantity of a Household Spray is 
Atomized into a Peet-Grady Chamber in Order to Deter- 
mine THE Effectiveness of the Insecticide. 

(Courtesy of Hercules Powder Co.) 


Nj- f.,r^ 


\* ' •• «» -» J *• 

Fig. 17. Flies Knocked Down During a Peet-Grady Test are 

Picked Up and Counted. They are Then Transferred to a 

Cage to See How Many Recover Within 24 Hours. 

(Courtesy of Hercules Powder Co.) 



liMi-'-' '-^K^ 

. ::g^; .. 

Fig. 18. This Piper Cub Airplane is Spraying a DDT Formula- 
tion Over Mosquito-Infested Terrain. This Treatment Kills 
Mosquitoes and Larvae as Well as Adult Stages 
OF Their Life Cycle. 

(Courtesy of U. S. Dept. of Agriculture. Photo by Knell) 

( ';s ) 

Common Insect Enemies 99 

spreading typhus long before their body-dwelling descendants 
evolved. But, be that as it may. Kill the head louse! Get 
rid of him! At best he is a useless parasite; at worst he is a 
deadly killer. 

Before the days of DDT, various remedies for the treat- 
ment of lice were used. These included larkspur lotion, kero- 
sene in either vinegar or olive oil, and derris powders and 
lotions. With any of these materials, two or more treat- 
ments are required because they do not kill the eggs and they 
are not long lasting. Therefore, after you kill the lice you 
have to wait until the eggs hatch and then try to catch the 
new-born youngsters before they have a chance to enjoy their 
love life and start raising families. 

If you'll just remember that DDT has long-lasting prop- 
erties, you can readily see why it is effective against the head 
louse as well as the body louse. So grab the carton of 10% 
DDT powder and shake it thoroughly into Johnny's hair. He 
may object to having his brunet locks suddenly assume a gray- 
ish appearance, but he will forgive you when you explain 
that he will not have to wash his hair for at least ten days. 
The reason for this is that DDT has one thing in common 
with the other louscicides — it does not kill the eggs. There- 
fore, the powder must be left in the hair long enough to kill 
the young lice from all the eggs as they hatch. 

If Johnny happens to be one of those unusual boys who 
insist on washing their hair the day after treatment, a second 
application of DDT powder should be made about 8 or 10 
days after the first in order to get rid of the animal life that 
hatches from the eggs left in his hair. The lice that hatch 
during this 8- to 10-day period will not complicate the prob- 
lem by laying more eggs, for it takes at least 10 days, and 

100 DDT — ^Killer of Killers 

usually longer, for the new-born creatures to become sexually- 
mature adults. 

Those who are in a hurry to get rid of the eggs as well 
as the lice can make use of the NBIN formula, which was de- 
veloped during the war particularly for the control of the 
body louse, but which is equally effective against the head 
and crab lice. This material is applied in emulsion form, 
one part of concentrate to five parts of water. The hair is 
thoroughly wetted with the emulsion, and is then combed to 
insure a more thorough distribution. Although the eggs as 
well as the lice themselves are killed by a single treatment, 
it is a good idea to leave the material on the hair for 8 or 10 
days in order to be sure that you get any lice that may have 
been hiding in your clothing while you were treating your 
hair. Since this material will retain its killing properties for" 
at least two weeks after application, any stray lice that re- 
turn to their home will wish they hadn't. 

You probably will not be interested in mixing up some 
NBIN, but your druggist or your chemist friend can do it for 
you, for NBIN concentrate is merely a mixture of 68 parts 
of benzyl benzoate, 12 parts of benzocaine, 6 parts of DDT, 
and 14 parts of a dispersing agent, such as Tween 80. 

Right Where If Hurts 

The crab, or pubic, louse is not known to transmit dis- 
ease, but he can sure make you miserable. He seems to know 
that scratching, particularly around certain parts of the hu- 
man body, is frowned upon in good society. Therefore, he 
makes his home principally in the pubic region where he can 
bite those tender parts to his heart's content, knowing that 
you will do no more than merely squirm in your chair. 

Common Insect Enemies 101 

This louse, which gets its name from its crabiike ap- 
pearance, is shorter and much flatter and broader than his 
relatives, the body and head lice. And, unlike the body 
louse, the crab louse does not live in the clothing, but makes 
his home in the hair of the body. Therefore, it does no good 
just to put on clean clothes; you must use an insecticide 
which will kill him on the body. 

In the past, Blue ointment, kerosene in vinegar or olive 
oil, and derris and larkspur lotions have been used against 
the crab louse, but DDT powder or the NBIN formula are 
much more efi^ective, and are not as irritating to tender parts 
of the body as are derris or kerosene-containing preparations. 

Since the crab louse lives in the hair of the body, all 
hairy portions, including the armpits, chest, the pubic and 
perineal region, and the legs should be thoroughly dusted 
with 10% DDT powder or treated with an emulsion of the 
NBIN formula, and the powder or emulsion should be rubbed 
in well with the fingers. One application of the NBIN 
formula will eradicate an infestation. It should be allowed 
to remain on the body for at least 24 hours in order to get any 
wanderers who were hiding out in the bedding or clothing. 
If you prefer to use the powder, leave it on for at least 2-1 
hours before you take a bath, and repeat the application in 
about 8 or 10 days. 

Your Bedtime Companions 

Have you ever noticed how a person aas just after he 
is shown to his room in a hotel or rooming house? How he 
tiptoes very carefully over to the bed, grabs the covers, and, 
with a mighty heave, pulls them down? What he is seeking 
are some tiny, brown creatures, with the scientific name of 

102 DDT— Killer of Killers 

Cimex lectularius, but known far and wide as bedbugs. These 
creatures don't like the light, and our hotel guest has to 
move plenty fast if he expects to get a glimpse of them be- 
fore they scurry to their hiding places. 

Of course, another way to find out if a hotel is, or has 
been, infested with bugs is to look for bedbug powder on the 
mattress or to sniff the mattress to see if it has been sprayed 
with an insecticide. Since many of the preparations that 
have been used for bedbug control are not very effective, evi- 
dence that they have been used is usually a warning that dur- 
ing the night, ii you remain awake, you will feel numerous 
sharp stabs as the bedbugs come out for their midnight snack. 

If your hotel manager is smart, he can make certain 
that you will be the sole occupant of the single bed for which 
you will pay $5.50 in the morning. Even though some pre- 
vious occupant of the bed may have brought to it a few choice 
specimens of bedbugs, there is no reason why the bugs should 
be permitted to perpetuate their race. For DDT is the per- 
fect answer to bedbug control! 

Either a spray of 5 % DDT in deodorized kerosene or 
a 10% DDT powder will do the job. One treatment with 
either of these formulations will not only clean up the bedbug 
infestation, but will prevent re-infestation for at least 6 
months and possibly for over a year. Three fluid ounces of 
the 5 % solution or two ounces avdp. of the powder are suf- 
ficient to treat a double bed. But be sure to do a thorough 
job: spray or dust both sides of the mattress and pillows, the 
bed springs, and particularly the cracks and joints in the bed- 
stead. Also treat the cracks and crevices along the window 
and door frames, behind pictures on the walls, and along 
baseboards and mouldings. All of these dark places may 
be hideouts for the bugs. 

Common Insect Enemies 103 

Whether to spray or dust is up to you — both are effec- 
tive. But the use of the powder is indicative of the fact that 
bedbugs formerly occupied the premises, and the guest will 
probably spend the night imagining that he is being bitten, 
even though the bedbug population was reduced to zero long 
ago. The spray, particularly if a good deodorized kerosene is 
used, will leave no tell-tale deposit or odor. Of course, when 
the spray is used it takes a few hours for the solvent to evap- 
orate, and the bed cannot be made up until it is dry. Inci- 
dentally, neither the powder nor the residue left after the 
evaporation of the spray solvent will harm your skin. So 
rest in peace — don't worry about either bedbugs or DDT 

The Ubiquitous Fly 

He drags his legs through the frosting of your freshly 
made cake; he dunks his head in your glass of milk; and he 
flies over to lap up that little drop of milk on the nipple of 
the baby's bottle. But where was he an hour ago: crawling 
around on the manure pile, exploring the privy, or floating 
leisurely down the sewer on an unattractive piece of debris? 
That's the housefly — Musca domestica — for you. Here, 
there, and everywhere, but always up to no good. 

Garbage, manure, and sewage are the preferred breed- 
ing places for flies. Here they lay their eggs, and within a 
period of about a week the eggs hatch to maggots, the mag- 
gots change to pupae, and the pupae develop into full- 
fledged flies ready to start a new generation. And since flies 
can live about a month, they can become the parents of nu- 
merous offspring before they finally pass on. In fact, it has 
been estimated that a single pair of flies left to enjoy life un- 

104 DDT— Killer of Killers 

molested could become the parents, grandparents, etc., of 
about six trillion descendents in about six months. 

If he were just a nuisance, we might grin and bear it, 
hard as that might be to do. But there is considerable evi- 
dence that old Musca domestica is public enemy No. 1, for he 
has probably committed more murders than all the gangsters 
and highjackers have ever committed. However, he is very 
tricky: it is about as hard to get the evidence on him as it is to 
convict a gang leader for anything except income-tax eva- 
sion. Everyone believes him to be guilty, but no one has 
been able to prove it. 

We all know that during the warm summer months 
there are veritable epidemics of what is politely called "in- 
tesinal flu," but which is actually a whole group of diarrheas 
and dysenteries of bacterial or other origin. How these dis- 
eases are transmitted is not clear, but since these are intes- 
tinal diseases, the organisms that cause them are found in 
copious quantities in human feces, and it is at least possible 
that flies might carry the organisms from the feces of an in- 
fected individual — or from sewage — to food which is sub- 
sequently eaten by another. If this is true, better waste dis- 
posal and a systematic campaign to eliminate the fly should 
help to reduce the spread of infections. However, before 
we place too much blame on the fly, we should be honest and 
admit that there would probably also be less spread of in- 
testinal infections if food handlers were more careful to wash 
their hands thoroughly upon leaving the toilet. 

Flies and Polio 

Poliomyelitis, or, as it is commonly but inaccurately 
called, infantile paralysis, is a dreaded disease. Few dis- 

Common Insect Enemies 105 

eases of modern times strike more fear into the hearts of men 
than this virus infection which attacks the nerve cells that con- 
trol the muscles, and which may leave its victim a cripple for 
life. It is this crippling aspect of the disease that is so 
frightening. Actually, polio kills fewer people than such 
common diseases as measles, whooping cough, and mumps. 

Although it seems to have reached epidemic proportions 
only within the present century, poliomyelitis, apparently, is 
an old disease, and is much more prevalent than most of us 
believe it to be. Probably most adults have had polio at 
some time during their lives without knowing it, for contrary 
to common belief, most cases of polio do not end in death or 
paralysis; it is only those cases that do show the typical paral- 
ysis that are recognized as such by most physicians. Cer- 
tainly, many adults have protective substances in their blood 
that immunizes them against further attack, and this indicates 
that they probably had the disease in a mild form earlier in 

But this knowledge doesn't help much when we see a 
number of children suddenly stricken with the disease in its 
violent form, and watch them die or become paralyzed. 
What causes the disease? How is it transmitted? And 
what can be done to prevent its spread? These are the ques- 
tions to which we would like to know the answers. 

Apparently the virus of poliomyelitis enters the victim 
through the mouth, or possibly the nose, and gets into his 
alimentary tract from where it travels to his nervous system. 
The evidence for this is that the virus has been found in hu- 
man stools and in sewage. How then, is it transmitted? 
Flies may be the answer, for poliomyelitis virus has also been 
found in flies. But more dramatically still, food left ex- 
posed to flies for from 12 to 24 hours in several epidemic 

106 DDT — Killer of Killers 

areas in 1944, became contaminated with the virus, as was 
revealed when the food was fed to chimpanzees. These ani- 
mals, although they did not show any evidence of paralytic 
poliomyelitis, showed virus in their stools for the next few 
months, and this virus when passed on to monkeys caused 
typical poliomyelitis lesions. 

Do flies play the same part in the transmission of polio 
that mosquitoes do in malaria and yellow fever? We don't 
know. But let's kill the flies and see what happens to the 
spread of polio. 

The summer of 1945 was a good time to try out this 
idea, for Rockford, Illinois was stricken with a severe polio 
epidemic, and the effectiveness of DDT had been well estab- 
lished. Within a few weeks, 17 people had died from polio 
in Rockford, and many times that number were ill. Get 
out the DDT! And that is what Dr. John R. Paul of Yale 
University and the scientific expedition that he headed did. 
The town of Rockford was sprayed, and sprayed thoroughly, 
and many flies paid the penalty for their possible association 
with polio. The polio epidemic gradually subsided, but 
whether the DDT campaign contributed to the decline is not 
known. It takes more than one experiment to gi\Q conclu- 
sive results. 

Some day we may know the role of the fly in the spread 
of polio, and if we find out that he is a killer as well as a 
nuisance, we can be sure that an aroused populace will fill 
its spray guns with DDT and wage relentless warfare against 
this flying carrier of filth. 

The Fly and the Horse 

Have you ever stopped to consider the relationship be- 

Common Insect Enemies 107 

tween the fly and equine populations? Unless you are a 
member of the younger generation you can remember the 
days when our city streets were covered with evidence that the 
horse reigned supreme in the field of transportation. He 
pulled the milk wagon, the grocer's delivery wagon, and the 
brewery truck; and the surrey with the fringe on top was a 
reality instead of a popular song. 

Being uninhibited in their toilet habits, the multitude 
of horses furnished work for numerous white wings; but it 
was a losing battle for the pushers of the broom: their task 
was never finished. This was a paradise for flies : they liked 
the manure-covered streets, and the manure piles behind every 
stable furnished ideal breeding places for them. The result: 
flies, flies, flies! Every time one went into or out of the 
house, a swarm of flies, lurking around the screen door> made 
a dash for the cooler interior of the house and the tempting 
food upon the dining room or kitchen table. 

Who could visualize in the early days of this century 
that the chugging one-cylinder horseless carriage would some 
day banish the horse from the city streets, and with it, the fly? 
Yet, that is what has happened. In our metropolitan areas 
today, the old gray mare "ain't what she used to be," and the 
fly is a negligible factor in the transmission of disease. 

In rural regions, however, the fly is still with us in quan- 
tity, for the tractor has not yet eliminated the horse, and no 
one has invented a satisfactory substitute for milk or beef- 
steak. The farmer, however, can now make his premises as 
free from flies as city streets by simply treating his barns and 
animals and manure piles with DDT compositions. Just 
to give you a few examples: In experiments where manure 
piles were treated with a /4 % DDT solution, no flies subse- 
quently emerged, and barns sprayed with DDT solution 

108 DDT— Killer of Killers 

showed a 99% reduction in the fly population even 30 days 
after treatment. 

An Island Paradise 

Out in Lake Huron, off the northern tip of the lower 
peninsula of Michigan, lies Mackinac Island, a delightful 
spot where the cool lake breezes keep the temperature down 
to reasonable levels during the summer months when folks 
swelter in their city homes. It is no wonder, then, that 
Mackinac Island has been a noted summer resort for many 
years. The island is rather large, and vacationers at resort 
hotels don't like to walk. In the days when Mackinac Island 
first became a summer resort, the horse and carriage were the 
fashionable means of transportation over short distances, and 
horses and carriages became as much a part of the island 
scene as the fat dowagers who eased their broad posteriors into 
chairs on the hotel's veranda. 

A few hundred miles to the south of Mackinac Island, 
in a city called Detroit, a new mode of transportation was 
perfected, and the product of Henry Ford and others could 
soon be found in practically every remote corner of the earth 
— but not on Mackinac Island. The proprietors of the re- 
sorts decided that the exhaust of motor cars would not be 
allowed to contaminate the pure lake air, and that the soft 
neighing of the horse was preferable to the noise of the 
horseless carriage. So today when you step off the steamer 
at the dock, you will be met, as were your parents and grand- 
parents, by a line of horses and carriages to transport you to 
your destination. 

But life on Mackinac Island has not been entirely a bed 
of roses, for the penalty for retaining the horse has been a 

Common Insect Enemies 109 

plague of flies. And it is difficult indeed to enjoy peace and 
quiet while pesky flies are buzzing around and biting chunks 
out of one's epidermis. 

And then came DDT! The Mackinac Islander's were 
not impressed when they heard about the remarkable ef- 
fectiveness of this insecticide against the typhus-bearing louse. 
After all, only well-heeled gentry are encouraged to spend 
their time on this oasis in a mechanical age. And it can be 
presumed that body lice are quite rare among folks who 
take a bath every Saturday night. But when it was learned 
that DDT and flies are incompatible, the natives pricked up 
their ears. Why not have one's cake and eat it, too? Or in 
plain words, why not keep the horses, but get rid of the flies? 
Spray the island from one end to the other with DDT. That 
ought to do the trick! And it did! For the first time in the 
memory of the oldest inhabitant, Mackinac Island was free 
from flies. A public celebration was held to celebrate this 
epoch making event; a huge bonfire was made, and the glee- 
ful citizens burned their fly traps. Perhaps, later on, they 
wished they hadn't, for flies breed rapidly, and a few surviv- 
ing members of the species can soon repopulate wide areas. 

Contenf-ed Cows 

With our typical conceit, we always look at every prob- 
lem from our own point of view. We believe that in our 
battle with the inseas we have right on our side. They attack 
us and, therefore, we have the right to kill them. But one 
could put up a good argument to the effect that inseas have 
as much right to the earth as we have — perhaps more, since 
they have been here longer. Most of us wouldn't even listen 
to such an argument, for, after all, aren't we God's chosen 

110 DDT — Killer of Killers 

creatures? And when one section of mankind fights another 
in our periodic wars, doesn't each nation maintain that God 
is on its side? But what we meant to talk about was cows. 

Insects attack us; but they also attack other animals. 
Ordinarily this would not interest us in the least, but where 
the cow is concerned we do take a personal interest. Our 
interest, of course, is entirely selfish. The mere fact that 
cows might suffer from fly bites is not, in itself, sufficient rea- 
son for us to kill the flies that attack the cows. But we get 
milk from cows, and — at least so we have been told — a cow 
must be contented if she is to give large quantities of whole- 
some milk. 

It is very fitting, therefore, that the Walker-Gordon 
Farms — where they specialize in contented cows — should 
have been one of the first dairies to use DDT on a large scale 
to cut down the fly population. Results were very gratify- 
ing: the fly population was cut to almost zero and, we pre- 
sume, the cows in appreciation of their increased contentment 
reciprocated by increasing their yield of milk. 

In the few years since DDT first became available, 
thousands of dairy barns have been treated with no damage 
to the livestock but with a great improvement in Bossy's life 
and with more milk for the farmer. Reports indicate that 
cows pestered with flies giye 3 to 8 % less milk than their fly- 
free sisters. 

There are three species of flies that annoy cattle — the 
housefly, the stable fly, and the horn fly. Of these, the house- 
fly is the greatest nuisance because it is usually present in the 
greatest numbers, although swarms of the much smaller 
horn fly are often found on livestock. Unlike the housefly, 
which feeds on the body secretions of animals, the stable fly 
and the horn fly feed upon the blood of animals. The house- 

Common Insect Enemies 111 

fly lays its eggs in manure and decaying vegetation; the stable 
fly lays its eggs in fermenting plant produas; and the horn 
fly lays its eggs only on fresh cow manure. A knowledge of 
their breeding habits is of considerable help in the control of 
these inseas: treat manure piles and decaying vegetation 
with DDT and keep down the fly population. 

To kill the flies around the barn, both the building it- 
self and the cattle should be treated. A residual spray ap- 
plied to the walls of the barn twice a year — May and August 
for best results — will reduce the fly population to a very low 
figure, for all flies that touch the treated surface will die. A 
5 % DDT-kerosene spray, a 5 % emulsion, or a 2/4% disper- 
sion of wettable powder (approximately 2 pounds of 50% 
wettable powder to 5 gallons of water) are all satisfaaory 
for application to barns, but of these three, the wettable pow- 
der is perhaps the most popular, for it is nonflammable and 
it is not readily absorbed by porous surfaces — rough wood 
and concrete — such as are found in barns. For best results, 
a gallon of the 2 % % dispersion should be used for approxi- 
mately each 300 square feet of surface. 

For direct application to the animals, the oil solution, 
of course, should not be used, but either the emulsion or the 
dispersion of wettable powder can be applied without harm 
to the animals. A single application of about a 2% % emul- 
sion or dispersion of wettable powder, applied as a spray at 
the rate of about 1 quart per adult horse or cow, will effec- 
tively control the horn fly as well as other flies for a few 
weeks or more. When applying the spray, particular at- 
tention should be paid to the belly, rump, and back. 

An alternative method of applying DDT to animals is 
by means of a dip, but when a dip is used the concentration 
of DDT should be much lower than when a spray is used: 

112 DDT — Killer of Killers 

an emulsion diluted to about % % DDT gives good results. 
About 2 gallons are required for each adult animal. 

The Female of the Species 

The relentless battle between man and insects is often 
carried out indirectly: the insects destroy man's food, or, in 
the case of flies, contaminate it with disease germs. But 
there is nothing indirect about the mosquito. When you 
sit out on your lawn on a fine summer's evening, you are soon 
attacked from all sides by a buzzing, blood-thirsty horde, and 
your tender epidermis is soon punctured in numerous places 
by sharp, hollow swords. Nor is it any consolation to know 
that the attack would be twice as bad if the males, instead of 
just the females, had mouth-parts capable of piercing your 

Mosquitoes belong to that class of insects known as 
Culicidae, a very large family indeed, being composed of a 
few subfamilies and numerous species. Not all of the species 
attack man: in fact, many of the species aren't blood-suckers 
at all, and of the blood-suckers many prefer to feast on birds 
and on mammals other than man. To keep from getting 
too technical, let's limit our attention to the Culex, Anopheles, 
and Aedes mosquitoes, for these members of the subfamily 
Culicinae comprise our pesky household mosquitoes as well 
as the deadly carriers of malaria and yellow fever. 

The various species of the genus Culex are supposed to 
be harmless, as far as the transmission of human diseases are 
concerned, but no one will disagree with the statement that 
the word "nuisance" is a very mild term to apply to these 
widespread destroyers of our peace and quiet. And are we 
sure that they don't carry disease from man to man? It is 

Common Insect Enemies 113 

known that some species of Culex do transmit blood diseases 
of birds and animals, and it is not beyond the realm of pos- 
sibility that some of the baffling diseases of humans might 
also be transmitted by means of these unwelcome intermedi- 
aries. Let's not forget that not many years have elapsed 
since malaria was traced to Anopheles and yellow fever to 
Aedes, and still fewer years have elapsed since two other 
tropical diseases, dengue and filariasis, were shown to be 

The method of attack that has proved so successful in 
cutting down the population of malaria- and yellow fever- 
bearing mosquitoes is still the best: Eliminate their breeding 
places, or at least treat their breeding places so as to disrupt 
their normal cycle of propagation. Some mosquitoes lay 
their eggs on the surface of water; others lay theirs on the 
ground after the pools have dried out, and the eggs remain 
there until rain or melting snow refills the pools. The eggs 
of some mosquitoes hatch within a short time after they are 
laid; with most species, however, the eggs remain as such over 
the winter; and in certain other species, it is believed that 
the eggs may remain on dry ground for as long as several 
years, waiting for the rain that will enable them to hatch. 

The marshlands along the ocean, the innocent-looking 
meadow pond, the rain barrel alongside the house, the rain- 
filled tin cans on your refuse pile, these are the breeding 
places of mosquitoes. Here they lay their eggs, here the 
eggs hatch into larvae — those well-known "wigglers" which 
you have seen many times — here the larvae go through four 
molts and change into pupae, and here after two or three 
days, the pupae shed their skins and emerge as full-fledged 
flying mosquitoes. 

It's very simple, then. Get rid of the water and you 

114 DDT — Killer of Killers 

get rid of the mosquitoes! And if you can't get rid of the 
water, cover it with a film of oil so the larvae can't breathe. 
These are the methods that our army engineers applied so 
successfully in Panama, where they fought and defeated the 
yellow fever-carrying mosquito Aedes, the killer that had for 
so long held up construction of the canal across that narrow 
strip of land. 

But drainage or oil treatment aren't always feasible. 
You know that during a wet spell the mosquito population 
increases phenomenally. There may be no ponds or lakes 
or marshlands near, yet the mosquitoes seem to find plenty 
of places to breed. The damp woods and fields offer in- 
numerable little wet spots for mamma mosquito to lay her 
eggs and for the results of her love life to pass through their 
various stages of development. After all, a mosquito larva 
is not very big: it doesn't need much space. That's all right 
for the mosquitoes, but what are we going to do about it? 
Shall we try some DDT? 

We know that a DDT space spray or a shot from an 
aerosol bomb will knock for a loop any mosquitoes present. 
We also know that a residual spray leaves a deposit of DDT 
that lasts for several months and kills any mosquito that 
comes in contact with it. These methods are extremely ef- 
fective. The U. S. Public Health Service, in its battle against 
the malaria-bearing mosquito, treated the walls of practically 
all the sharecroppers' shacks within a 36-square mile area 
near Helena, Arkansas, with a DDT residual spray. Cost: 
74 cents per shack for material and labor. Results: A 94 % 
reduction in the mosquito population for at least 2 months. 
Not bad! 

Perhaps you are familiar with the ferocious and enor- 
mous mosquitoes that inhabit the miles of salt marshes along 




Fig. 19. To Kill Mosquito Larvae in Flowing Water, a Drip 
Can Feeding a DDT in Oil Solution is Very Convenient. 

(Courtesy of Geigy Company, Inc.) 


:*f . ■ ■--.■^ 

Mf' \ 

Fig. 20. A Rotary-Type Hand Duster Being Used to Treat a 
Mosquito-Breeding Place with DDT. 

(Courtesy of U. S. Dept. of Agriculture. Photo by Knell) 


Fig. 21. These Walker-Gordon Cows Will Be More Con 
TENTED After the Dairy is Sprayed With a Water 


i Courtesy of Geigy Company, Inc.) 



Fig. 22. Cows Kept Free from Flies by Direct Application of 

DDT Will Give from 3 to 8% More Milk Than 

Their Untreated Sisters. 

(Courtesy of Hercules Powder Co.) 


Common Insect Enemies 119 

the New Jersey coast and make periodic forays into the neigh- 
boring towns and villages to suck the blood of the hapless 
inhabitants and visitors. However, New Jersey is rather sen- 
sitive about its reputation as the mosquito capitol, and de- 
cided to do something about it. A DDT-oil solution sprayed 
over thousands of acres of marshlands killed millions of 
mosquitoes and made life in New Jersey much more com- 
fortable. Unfortunately, in their anxiety to do a good job, 
the mosquito exterminators used more DDT than was neces- 
sary, for the officials in charge were greatly disturbed to find 
that many fish also succumbed to this mass attack. 

You may also have read about what they did in New 
York to the mosquitoes along Jones beach — that magnificent 
stretch of sand that is covered in the summertime with a 
few beautiful and thousands of ugly, practically nude bodies, 
much to the delight of the mosquitoes. One fine day, before 
the bathers were permitted on the beach, clouds of a DDT-oil 
m.ixture were generated and were carried inland by the gentle 
ocean breeze. That afternoon and evening the bathers were 
pleased, but surprised, to find that their fat bodies were, for 
once, not blood banks for mosquitoes. 

For our military campaigns in the Pacific, mosquito 
control was essential. You have heard of how entire islands 
were treated with DDT and praaically all insect life elim- 
inated. One Pacific island of 6,400 acres was sprayed with 
a DDT-oil solution from a torpedo bomber, flying at a speed 
of 125 miles per hour at an elevation of 150 feet. Ten gal- 
lons of solution were sprayed per minute, and only 2 quarts 
were applied per acre. Yet, this was sufficient to wipe out 
all the insects. 

Saipan is a name that will long be remembered. In 
addition to the Japs, our fighting men there had to contend 

120 DDT— Killer of Killers 

with a dengue-type mosquito. An airplane was loaded 
with DDT powder instead of with bombs, the island was 
thoroughly dusted, and not a mosquito or fly was to be seen. 
Within a few weeks, dengue was no longer a problem to the 
medical service. 

But we were speaking about treating the breeding 
grounds of the mosquito. Let's get back to the subject. We 
said a while ago that oil applied to stagnant bodies of water 
will kill the larvae. But, one quart of 5 % DDT-oil solu- 
tion is as effective as 10 to 14 gallons of oil alone. In fact, 
DDT is probably the most effective mosquito larvicide yet 
developed. As little as %o pound of DDT per acre applied 
as an oil solution, a dust, or an emulsion to water surfaces or 
vegetation prevents the development of larvae for weeks. 
For stagnant waters, 1 part of DDT per 100,000,000 parts 
of water will kill the larvae and pupae of many types of 
mosquitoes, although for some species, a somewhat higher 
dosage is required. 

Ants in Your Pantries 

Ants are the delight of sociologists, for in social devel- 
opment ants are centuries ahead of man. A colony of ants 
busily engaged in carrying out the multitudinous activities of 
their daily life is a sight worth witnessing. Yet, it is a de- 
pressing experience, for one can't help but feel that ants know 
much more about efficient organization of community life 
than man can ever hope to learn. Watch the ants closely! 
Each one seems to know just what to do — and he does it. 
No strikes, no picket lines, no unemployment! But maybe 
ants are just dumb. What's the sense of working all day, 
every day? Where does it get you anyway? Nevertheless, 

Common Insect Enemies 121 

it is very intriguing the way ants do things. A few males 
and females are hatched, the males mate with the females 
and, having completed their life's work, immediately proceed 
to die, and then each inseminated female, or queen, estab- 
lishes a new community. To maintain her position as head 
of the new colony, the queen sees to it that her offspring for 
the next few years are all workers; and to make sure that the 
workers keep their minds on their work instead of mooning 
around, the mysterious law of the colony usually sees to it 
that the workers are sexless. A similar arrangement in hu- 
man society would have obvious advantages, but it is doubt- 
ful if the idea would be readily accepted by the mass of our 

One of the big tasks of the workers — perhaps the most 
important — is the gathering of food, not only for themselves 
but also for the queen and the numerous crops of developing 
larvae. Some ants find other insects very tasty, but most of 
the ants we encounter are vegetarians, by nature. And they 
are particularly partial toward sweets. As they forage over 
wide areas for their nourishment, some ants invariably find 
their way into your home and soon locate your hoard of sugar 
and other foods on your pantry shelves. If most of us 
stumbled upon what to us was an almost inexhaustible sup- 
ply of food we would keep that information to ourselves and 
would do our best to keep our neighbors from finding out 
about it. But that is because we are uncivilized. Ants are 
different. They are not selfish like we are: they immediately 
broadcast word of their discovery to all their fellow workers, 
and soon the safari is on. Where yesterday there was a 
single ant, today there are hundreds, all busily engaged in 
carrying away food that we had hoped to have for our very 

122 DDT— Killer of Killers 

The ant is probably not a carrier of human diseases. At 
least, if he is we don't know about it. When he stays out- 
side of domiciles, he doesn't bother us much except when we 
go out into the wide-open spaces for a picnic. And then it 
is our own fault: anyone foolish enough to spread a cloth in 
some grassy glen and cover it with food deserves no sympathy 
ii ants start carrying away the sandwiches. If we invade the 
home of the ant, he has a right to fight back. And if he in- 
vades our home, he deserves what he gets; and today what 
he gets is probably DDT. 

There are numerous species of ants, and not all of them 
can be controlled by the use of DDT, but it is very effective 
against many of the common species that invade the home. 
Either a 5 % DDT-kerosene spray or a 10% powder can be 
used for the control of ants in buildings. Since the spray 
leaves no noticeable deposit, you will probably prefer it. 
Spray behind and beneath baseboards, behind window sills 
and frames, about sinks in the kitchen and bathroom, all 
table legs and chair legs, both sides of pantry shelves, and all 
cracks and crevices leading to the outside of the building. A 
single application will control many species of ants for sev- 
eral weeks, and some species that do not respond to DDT 
alone can be eliminated by means of a 10% DDT dust con- 
taining Ko % pyrethrins. 

To clear away ants from nests, sprinkle a little 10% 
DDT powder around the openings to the nests. As the ants 
go in and out of their home they will walk through the pow- 
der, much to their great discomfort. As a result, the nest 
will usually be abandoned within a very short time. 

The Wood Eaters 

In this day of the housing shortage, many old houses 

Common Insect Enemies 123 

that have remained empty for many years suddenly acquire 
tenants. Sleeping in some of these houses is probably better 
than sleeping on park benches, for at least one has a roof over 
his head, even though it may permit the passage of copious 
quantities of rain. But although there may be a roof, there 
probably won't be much of a foundation, for although the 
house may not have provided shelter for humans for many 
years, it probably has been a source of food for many genera- 
tions of termites. 

Termites, or white ants, like the true ants, are highly 
developed social inseas. Each colony has its queen and, 
more surprising, it also has a king. Unlike the true ants, 
the male termite survives the nuptial night and continues to 
live in harmony with his mate, constantly displaying the af- 
f eaions that every wife has a right to expea from her spouse. 
But in addition to the royal family, there are the workers, 
usually sexually undeveloped, and a special caste of profes- 
sional soldiers with enormous heads and mandibles. Al- 
though it is not nice to make slighting remarks about the 
military caste, the evidence is that the soldier termites don't 
do a very good job of protecting the colony. Like the mili- 
tary castes of many of our nations, the termite soldiers have, 
apparently, assumed a position of importance all out of pro- 
portion to their true value. 

The common termites make their homes in the ground 
and send out tunnels to building foundations, wooden floors, 
and other sources of cellulose, which they are able to digest 
by means of certain bacteria in their intestinal traas. Re- 
gardless of how much we dislike these destroyers of our 
homes, we must admit that they are good engineers. They 
always leave enough of a timber to prevent it from collapsing 
on them. Thus, at first glance the foundation of your pro- 

124 DDT— Killer of Killers 

spective home may look pretty good; but if you penetrate the 
outer shell you will probably find nothing but a sponge-like, 
honeycomb structure which will collapse when subjected to a 
little extra stress. 

Perhaps the best thing to do if you have termites around 
is to get out the 5 % DDT-kerosene mixture and treat the 
soil around the timbers you want to protect. One treatment 
will remain eifeaive for at least two seasons. 

A Dog's Life 

When Fido stretches out on the living room rug for a 
well-deserved rest after a day of chasing cars or just hanging 
around with his girl friend, he doesn't rest peacefully. Every 
few minutes he twists himself into some grotesque position 
and scratches his neck or some other portion of his anatomy 
with his hind legs. Or else he gives a little bark and sud- 
denly sinks his teeth into the hair on his belly as he tries to 
bite a savage little devil with a formidable mouth equipped 
for piercing the skin and sucking the blood. 

And if you are the owner of a dog or cat, you know 
what a flea bite feels like, for fleas do not hesitate to vary 
their diet with a little human blood. If for no other reason 
than that he is an annoying pest, the flea deserves to be ex- 
terminated. But he is more than that — he is one of man's 
most dangerous insect enemies. Untold millions of humans 
have lost their lives from diseases transmitted by fleas. Bu- 
bonic plague — the infamous Black Death of the l4th cen- 
tury — is still with us, and this disease is known to be trans- 
mitted from rats to men by the bite of the rat flea. And 
even the dreaded typhus, which is transmitted principally 
from man to man by the louse, seemingly originates in rats 

Common Insect Enemies 125 

and gets started in man by the bite of a flea. How many 
other diseases we acquire in a similar manner we don't know, 
but a mass of evidence is accumulating to show that many 
animals and birds, both wild and domesticated, can act as 
carriers of human diseases, and that these diseases are trans- 
ferred to our bodies by the bites of fleas, ticks, and mites. 

There are several hundred species of fleas, but they are 
all similar in habits and resemble each other in appearance. 
If all species would remain exclusively with their preferred 
hosts it would not be so bad. But they don't. A rat flea 
may prefer a rat to a man, but when a rat dies and the fleas 
leave him, they'll become companions of men if no rats are 
readily available. And as for cat and dog fleas, they make 
themselves right at home in our houses. 

The eggs of fleas are laid on the body of the host ani- 
mal, but they either fall off or get shaken off to the ground or 
floor. Thus, they become scattered about the floors of dwell- 
ings and the sleeping places of infested animals. Carpets, 
rugs, upholstered furniture, and even your bed may become 
depositories of flea eggs. And here the eggs hatch to larvae. 
The larvae are not parasites: they find enough food in the 
decaying animal and vegetable matter in the dirt in which 
they live. But when they become adults, they change their 
habits. Now they live on animals. 

Since dogs and cats are about the only animals that 
people ordinarily permit to share their homes, the common 
fleas that you are likely to encounter are dog or cat fleas. Of 
course, if rats inhabit your premises there will probably be 
some rat fleas around, too. 

To get rid of fleas on dogs, dust the animals thoroughly 
with 10% DDT powder — about 1 tablespoonful is sufficient 
for an average-size dog. The fleas will start to die in about 

126 DDT— Killer of Killers 

10 minutes, and within about two hours they will all be dead. 
However, since DDT aas as an intoxicant, the fleas show in- 
creased aaivity for some time after the dog is dusted. One 
advantage of the DDT treatment is that the dog will remain 
free from fleas for at least several days after a single appli- 
cation. Therefore, a dusting once a week should keep your 
dog perpetually flea-less. 

But treating the animal itself is not enough since the 
eggs and larvae are scattered around the house. Therefore, 
you should spray the sleeping places of dogs, and infested 
floors, rugs, overstuffed furniture, basements, and rat bur- 
rows with 5 % DDT-kerosene spray. Or, for those areas 
where staining or a powdery deposit can be tolerated, a 10% 
DDT powder, a 5 % DDT emulsion, or a 2 % % suspension 
can be employed in place of the kerosene spray. DDT is 
particularly effective against flea larvae, so treating the prem- 
ises is particularly advantageous since it kills the insects be- 
fore they reach the biting stage and hop on your dog or bite 
your leg. 

Unfortunately, since cats lick themselves, they should 
not be treated directly with DDT powder for they might lick 
enough to become sick. However, treatment of their sleep- 
ing places and other infested areas, as described above, should 
be sufficient to get rid of the fleas. 

Tick, Tick 

Dogs not only harbor fleas, they also have ticks. And 
these little blood-sucking insects are just as bad to have 
around as fleas. Of course, your dog is by no means the 
only host to ticks: there are hundreds of species of ticks, and 
they are found on praaically all kinds of domesticated and 

Common Insect Enemies 127 

wild animals and birds. Among the diseases that ticks carry 
is Rocky Mountain spotted fever, which is transferred from 
certain species of rabbits, and possibly other rodents, to 
hunters, trappers, and campers who are unfortunate enough 
to get bitten by ticks that had been living on diseased animals. 

Although the various spotted fevers have not yet reached 
epidemic proportions, there is always the possibility that a 
terrible epidemic might break out at any time, for many 
species of animals and birds are reservoirs of these diseases, 
and these animals all have ticks which can, if given a chance, 
puncture your skin and inject the deadly virus. The poten- 
tialities of the situation are quite evident from the fact that 
the American dog tick can transmit the eastern strain of 
spotted fever. The moral is : get rid of the ticks. This is not 
too difficult. Premises of residences, parks, and camp sites 
can be freed from this tick by spraying the vegetation with a 
Vi % DDT emulsion at the rate of 3 pounds of DDT per 
acre. However, for direct application to infested animals, 
DDT dusts and dips have not proved as effective as the older 
rotenone preparations. 

As far as you are concerned, the American dog tick may 
be of little interest, for the common tick of dogs is the brown 
dog tick. Fortunately, this tick can be controlled very nicely 
with DDT. In fact, treatment of the animal and the in- 
fested buildings for the control of fleas will also control the 
brown dog tick. So just use the 10% DDT powder on the 
animals and the spray or powder around the house and 
everything will be under control. But when treating build- 
ings, be sure to dust or spray the cracks and crevices around 
baseboards, for these provide good hiding places for ticks. 

We can't go into a lot of details for the control of all 
kinds of ticks, but horse lovers might be interested in the 

128 DDT— Killer of Killers 

fact that a single treatment of horses with %o% DDT in 
soluble pine oil emulsion will kill the winter horse tick and 
prevent reinfestation of the animals for a few months. And 
our poultry raisers might like to know that a single treat- 
ment with a 5 % DDT-kerosene residual spray will keep their 
poultry houses free from ticks for at least three months. The 
spray, of course, is not applied to the chickens, but to the 
perch holes, and cracks and crevices in the poultry house, and 
other potential hiding places of the fowl tick. 

Down on the Farm 

We have spent considerable time telling you about 
a number of insect pests that make life miserable for you, and 
have told you how DDT can alleviate your misery. Let's 
now devote a little attention to some other insect enemies, 
who, like the late Adolph Hitler, are strict vegetarians. We 
told you a while back how DDT won its spurs when it saved 
the Swiss potato crop. Let's see what else it can do for our 
hard-working farmers and for our numerous gardeners who 
spend the hot summer months trying to breathe some life in- 
to a row of wilting lettuce. 

A few mosquitoes on your skin may raise a few lumps 
and cause you to scratch — and, incidentally, to swear — but a 
horde of pretty striped beetles can ruin the farmer's crops, 
causing him to lose a lot of money and, as a result, raising 
your food bill. From a purely dollar-and-cents point of view, 
DDT means much more to the farmer than it does to the 
apartment-house dweller, whose entomological knowledge is 
limited to flies, mosquitoes, ants, moths, and perhaps cock- 
roaches. It's a little too early to get the whole story about 
DDT for agricultural purposes, for it takes several years of 

Common Insect Enemies 129 

testing to find out what an insecticide can or can't do against 
the multitude of plant pests, but a lot has been found out 
in the few years since the lethal properties of DDT were 
first discovered. Here are just a few examples: 

In addition to its great effectiveness against the Colorado 
potato beetle, as was mentioned in an earlier chapter, DDT 
is highly effective against a number of other insects that at- 
tack potatoes, as well as those that attack peas, beans, cab- 
bages, corn, onions, cotton, and many other field crops. 
Furthermore, it does a fine job against the numerous moths 
and other inseas that attack fruits — ^peaches, apples, pears, 
grapes, citrus fruits, and others. The flower lover will be 
interested to know that DDT is probably the best insecticide 
to use on his rose bushes as well as on his chrysanthemums, 
snapdragons, and other flowers. If you are not a gardener 
or a farmer, and if you would rather buy your flowers at the 
florist than raise them yourself, this information will leave 
you cold. But if you do engage in 'green thumb" activities, 
you will want to know more about it. To satisfy everyone, 
we have devoted a latter section of this book to specific uses 
for DDT in agriculture, and there we tell you what prepara- 
tions to use and how to use them. But whether you raise 
food or merely eat it, you should know that DDT should not 
be used on fruits or vegetables such as cabbage in the later 
stages of their development, for under such conditions suf- 
ficient DDT might be left on the produce as it goes to market 
to give the consumer a slight case of poisoning. However, 
if satisfactory methods are developed to remove DDT from 
fruits after they are harvested, it will probably prove advan- 
tageous to continue the use of DDT for a longer portion of 
the growing season. 

In order to give a complete picture, it should also be 

130 DDT — ^Killer of Killers 

emphasized that DDT can't be used safely on all plants, for 
some species of the vegetable kingdom are poisoned by it. 
For example, it is harmful to cucumber and melon vines, and 
other curcubits. And, it should not be used on tomato plants. 
The best advice we can give is: Follow the instruaions on 
the label of your insecticide, and heed the advice of your local 
agricultural specialist. 

Beauty and the Beasties 

Butterflies and moths are lovely creatures. With their 
gaily colored wings and their gentle, unhurried motions, they 
seem to us to be the aristocrats of the insect world. But 
every school child knows that in an earlier stage of develop- 
ment these beautiful, carefree, flying insects are nothing but 
ugly, squirmy caterpillars, whose only object in life seems 
to be to eat up all the vegetation in sight. Remember how 
our teachers in the first or second grade used to tell us about 
the silkworm? Of course that was way back before the 
Pearl Harbor episode, in the days when Japan was a group 
of beautiful islands known to most Americans chiefly for its 
kimonos, rice, chop sticks, and geisha girls. Anyway, our 
teachers used to tell us that the silkworm moth would lay 
her eggs, the eggs would hatch to caterpillars — the silkworms 
themselves — and the worms, after gorging themselves on 
lots of tender mulberry leaves, picked by the slender hands 
of Japanese maidens, would eventually wrap themselves up in 
silken cocoons, in the hopes that some day they would emerge 
as their ancestors did, as full-fledged flying moths, ready to 
heed the call of nature to perpetuate their race. 

Alas for most of these dreams: the Japs would take the 
cocoons and dunk them in hot water to kill the worms in- 

Common Insect Enemies 131 

side, and then they would unwind the silk which eventually 
would be converted into sheer hosiery to cover some beautiful 
and many not-so-beautiful American legs. This, however, 
was long ago. Things have changed a lot since the Ehi Pont 
Company, by virtue of clever advertising, convinced our 
American females that if they want to be whistled at — and 
what woman doesn't? — they must encase their underpinnings 
in Nylon. 

But take your choice, Nylon or silk. We don't care! 
In fact, if your legs are sufficiently free from blemishes and 
not too fuzzy, go around barelegged. We only mentioned 
the silkworms, anyway, as an example of the relationship be- 
tween butterflies and moths and caterpillars. And we aren't 
going to get into an argument as to the difference between 
moths and butterflies. Our bug collector friends tell us that 
they are both members of the class of inseas known as 
Lepidoptera, and as far as we can find out the division of this 
group of insects into butterflies and moths is entirely an 
artificial one. In general, moths fly at night and butterflies 
fly in the daytime. Furthermore, when butterflies are at 
rest they generally fold their wings together above their backs 
in a vertical position, while moths either wrap their wings 
around their bodies, spread them horizontally, or fold them 
in a roof -like manner over their abdomens. To all of which 
you will probably say: "So what?" 

But to get down to business. Moths and butterflies, 
in spite of their beauty, are very destructive. Not that they 
do direct damage, but because they are the parents of tril- 
lions of caterpillars, each of which eats many times its weight 
of vegetation. These are the inseas that destroy millions of 
dollars worth of fruit a year, as well as our shade and forest 
trees. And of course, one member of the species dearly loves 

132 DDT — ^Killer of Killers 

your winter suit and any other woolen garments you may 
have around. 

Perhaps you are familiar with the gypsy moth, one of 
the most destructive pests of fruit and forest trees we have, 
particularly in the eastern part of the country. Although it 
doesn't make much difference any more, the gypsy moth is a 
native of Europe, and was brought to this country in 1866 
by a French naturalist who was experimenting with silk- 
worms. Some of his specimens escaped to the woods, and 
now we spend millions of dollars a year in trying to control 
this one insect alone. 

But now DDT has entered the battle between man and 
the moth, and the moths had better watch out, for they just 
can't take it. Spray your clothes and other woolens with a 
5 % DDT solution, and the deposit left after evaporation of 
the solvent will keep your garments free from moths for at 
least six months. However, if you have your clothes dry 
cleaned, the naphtha or other solvent your cleaner uses will 
dissolve out the DDT, so you will have to re-spray the 
freshly-cleaned garments. Deodorized kerosene can be used 
as the solvent for your DDT moth-proofing spray, but you 
will probably prefer to have the DDT dissolved in cleaner's 
naphtha, for it evaporates much more rapidly than does the 
kerosene. Incidentally, DDT kills both the adult moths and 
the larvae by contact. 

For the control of the gypsy moth, tent caterpillar, and 
similar pests on your shade and fruit trees, you will probably 
prefer to use a spray prepared with about 1 pound of 50% 
DDT wettable powder per 100 gallons of water, or an emul- 
sion containing about /4o% DDT. For large areas of for- 
est trees, the application of a DDT-oil spray or an emulsion 

Common Insect Enemies 133 

by airplane is not only effective but very economical. Let's 
look into the matter a little more thoroughly. 

Homes in the Raw 

With millions of men and women searching frantically 
for non-existent homes, the housing shortage has developed 
into perhaps the principal postwar headache. And houses, 
at least most of them, are built from lumber. We no longer 
have to be preached to by conservationists to be impressed 
by the fact that our forests are among our most important 
natural resources. When you have to pay $80 or more a 
thousand feet for unseasoned, knotty boards you know that 
a good tract of timber land is worth more than a good gold 
mine. You also realize that any destruaion of our timber 
reserves affects not only the owners of the tracts, but all of us. 

Signs in our forested areas admonish us to "Break your 
match! Put out your campfire! Help to prevent forest 
fires!" Forest fires take a terrific toll of forest trees every 
year, as blackened stumps all over the country testify. And 
everything we can do to prevent such destruction should be 
done. But what about the less spectacular but greater de- 
struction caused by the ravishes of insects? A news item 
about how Montclair, New Jersey, faces the loss of its more 
than 4,000 elm trees because of the Dutch elm disease does 
call our attention to the faa that even mighty trees can fall 
prey to enemies of insignificant size, and anyone who sees his 
favorite shade trees dying in the prime of their lives cannot 
help but feel a little sad. Try to imagine, then, destruction 
of this type multiplied many thousand fold, for that's what 
is happening to our forests. 

Among the serious insect pests that are ruining our 

134 DDT— Killer of Killers 

forests are the spruce bud worm; the gypsy, brown-tail, and 
pine-tip moths; the hemlock looper; the Saratoga spittle bug; 
the red-headed pine sawfly; and the white pine weevil. Of 
course there are many others, but that gives you some idea 
of what our forest trees have to contend with. 

The Agricultural Research Administration of the U. S. 
Department of Agriculture, in cooperation with several other 
organizations, has carried out a number of investigations on 
the control of forests insects by the use of DDT. Although 
much still remains to be learned, there is no question about 
the effectiveness of this new insecticide. In general, no more 
than a pound of DDT per acre is required, and this amount 
will not kill birds or animals. In fact, with proper methods 
of application, /4 pound per acre, or even less, is sufficient, 
and where there are fishing streams to be considered, not 
more than /4 pound should be used. DDT emulsions, and 
even suspensions, have given good results when applied by 
aircraft, but most of the work has been done with rather con- 
centrated solutions of DDT in oil. The DDT is first dis- 
solved in xylene or some other excellent solvent, and then 
this solution is diluted with fuel oil to a concentration of 
about 10 or 12 % DDT. Only a gallon per acre, or less, of 
the finished solution is required. The oil solution forms a 
tacky deposit of DDT on the trees, and this tacky deposit 
seems more effective than the deposit left by powder disper- 
sions. On the other hand, suspensions form larger droplets 
and less material is carried away by the wind, and suspen- 
sions are less toxic to fish. There is still much to be learned, 
but a lot has already been found out in the short time since 
the use of DDT against forest insect pests was first started. 


Fig. 23. This Pig Will Remain Free from Flies and Lice for 

A Long Time After Her Treatment With a 5Vf DDT 

Dispersion in Water. 

( Courtesy of U. S. Dept. of Agriculture. Photo by Madeleine Osborne) 


Fig. 24. Cattle on a Florida Ranch are Sprayed with 
DDT FOR Control of the Horn Fly. 

(Courtesy of Geigy Company, Inc.) 


Chapter Si 


Old Mother Nature 

The Balance of Nafure 

VV E have long been told by those who 
seem to know that there is a balance, or equilibrium, among 
the various forms of life on earth. One species of animals eats 
another, and in turn is eaten by a third. The inseas that eat 
your garden crop fall prey to birds, and birds fall prey to many 
other animals in addition to your pet cat. We are told of 
the classical example of Australia, where rabbits introduced 
by homesteaders soon overran the island continent because 
there were no foxes or coyotes or other natural enemies of 
the rabbit to keep the rodents from multiplying at a rate for 
which rabbits are famous. 

So the balance of nature was changed in Australia. And 
it is constantly undergoing changes everywhere else. The 
English sparrow and the gypsy moth were not natives of this 
continent, and when they were introduced into America 
there had to be a shift in whatever balance of nature existed 
before. And yet, in spite of the faa that there is nothing 
static in nature, many alarmists start shouting whenever a 
new insecticide is introduced, and their cry is always the 
same: "You will destroy the balance of nature!" To which 
we can only reply: "What if we do?" There is nothing 
sacred about the old balance anyway, and if it is shifted there 
is at least a 50-50 chance that it will be for the better — at 


138 DDT— Killer of Killers 

least as far as we are concerned. But actually, it's a lot hard- 
er to shift the balance of nature than many people assume. 
Your potato patch may be free from bugs today, but stop 
spraying or dusting and see how it is in a few weeks. The 
bugs will be back by the millions — their numbers seemingly 
unaffected by the temporary setback caused by your spray 

One thing that many folks worry about is the fact that 
DDT kills beneficial and harmless insects as well as those 
that cause us trouble. There is always the possibility that 
we may kill off more of the good bugs than the bad ones, 
and thus do more harm than good. But the chances of this 
happening are not very great. Even if every insect in a 
large forest area were killed, the area would be completely 
repopulated within a few weeks or months, as swarms of in- 
sects of every description moved in from the surrounding 

Of course, if all the insects on a whole continent could 
be killed, it would be interesting to see what would happen. 
But that we shall never see! In the first place, to treat a 
whole continent with DDT would cost a little money. The 
United States occupies about 2 billion acres of the earth's 
surface. Assuming a cost of $1.50 per acre for material 
and labor, it would cost about 3 billion dollars to spray the 
whole United States with DDT. Once upon a time this 
would have been considered out of the question. But not 
today! Not long ago this country granted Great Britain a 
so-called "loan" of 3% billion dollars, and during the war, 
between 2 and 3 billion were spent on the development of 
the atomic bomb. But even if, in some way, we could pro- 
duce the tremendous quantity of DDT required, and if we 
could get hold of the money, we probably would be disap- 

, Old Mother Nature 139 

pointed with the results. In the first place, even if we killed 
off all of the insects in the United States, we would soon find 
billions of insect immigrants entering this country from Can- 
ada and Mexico. But, of even greater importance is the 
fact that we could not kill all the insects. Some species are 
quite resistant to DDT and would survive the attack; and 
even among those species that are readily killed, a few in- 
dividuals are bound to escape. And even if 99 % of the in- 
sects of a certain species were killed, it would not take long 
for the remaining 1 % to re-establish the species on a large 

The Busy Bee 

From the movies, the radio, the newspapers, and the 
pulp magazines, our children learn the facts of life at an 
early age. To an older generation, the sweet little story of 
the busy bees carrying pollen from the papa flowers to the 
mamma flowers was the approved method of introducing a 
child to the mysteries of sex. Actually, however, the child 
who listened patiently to this roundabout explanation un- 
doubtedly learned much more from certain words scrawled 
upon the sidewalks and walls of outdoor toilets. 

And how often have we been told to follow the ex- 
ample of the bee and keep busy all the time? That's bad 
advice! The bee may keep busy buzzing around all day, 
but he doesn't accomplish much for his efforts; and in that 
respect he isn't much different from the supposedly more in- 
telligent human beings. But all this is beside the point. 

Although a bee's sting is a very unpleasant experience, 
we must admit that bees are useful inseas. We are all 
familiar with the produa of the honeybee, and we wouldn't 

140 DDT — ^Killer of Killers 

want anything to happen to the produaion of this deleaable 
confection. But of even greater importance is the role of 
the bee in the pollination of fruits, as mentioned above. It 
is easy to understand, therefore, why many orchardists be- 
came worried when DDT first came into use. What's to be 
gained if you kill off insects that attack the trees and at the 
same time kill the bees that are so essential for pollination? 
You can't blame our fruit growers for being worried, for 
laboratory tests showed that DDT will kill bees. 

Yet, like many another dire prediaion, the fear that 
DDT used on fruit and field crops would have a disastrous 
effect on bees has been proved to be unfounded. Actually, 
DDT is less toxic to bees than the arsenic sprays that have 
been used for many years. Thus, the substitution of DDT 
for arsenicals is actually to the beekeepers' advantage. But 
the case for DDT is even much stronger than that. 

Many large-scale experiments have been carried out in 
which DDT was dusted on fields adjacent to colonies of 
honeybees. It was found that the number of dead bees was 
no greater than normal. It is true that very few bees will be 
found in the treated fields for several days after the applica- 
tion of DDT, but they soon return in normal numbers. Ap- 
parently, the DDT merely repels them for some time. This 
should not be interpreted to mean that DDT does not kill 
bees, for it certainly does. If bees are actually hit by a DDT 
spray or dust, they will, in all probability, be killed. But in 
the concentrations used in most agricultural applications, 
there is not likely to be enough of a residual deposit to cause 
the death of bees that later enter the treated area. This has 
been verified by examining the dead bees around the hives. 

Insects that come in contact with residual DDT de- 
posits do not die immediately. Bees, for example, would 

Old Mother Nature 141 

have sufficient time to return to the hive before passing out. 
If they did that, it would be very unfortunate, for in that 
way they could carry DDT to the hive itself and bring 
about the death of the whole colony. But so far, at least, 
there is no evidence that bees pick up lethal doses of DDT 
and return to the hives to die. Either they don't get enough 
DDT to kill them, or else they get so much that they die 
right away; and there is no evidence whatever that the latter 
is the case. 

Obviously, one must use judgment when applying DDT 
to his crops, the same as he does when he uses it in his home. 
It would not be sensible to spray the blossoms of fruit trees 
when you knew that the bees would soon be on those very 
blossoms. The sensible thing would be to spray the trees 
before the blossoms opened — and no bees were around — 
and again after the bees had finished their task. Then there 
would be no possibility of leaving a residual deposit of DDT 
on the blossoms themselves. 

By the proper application of DDT, our bee population 
should be materially increased, for when destructive insects 
get in their work, plants are often so badly destroyed that 
they have few blossoms and, hence, little food for bees. Thus, 
treatment of alfalfa fields with DDT before bloom is very 
desirable from the bee's point of view as well as from the 
farmer's. The results can be summarized in a few words: 
Fewer insects, more flower buds, more bees, better pollina- 
tion, and more seed. 

Bees have been with us a long, long time. They have 
seen many insecticides come into use, and they will undoubt- 
edly see many more. So far, no insecticide has seriously af- 
fected our bee population, and DDT is less likely to do this 
than other popular inseaicides. Your chances of getting 

142 DDT— Killer of Killers 

stung by a bee a year from now will, undoubtedly, be every 
bit as good as they are today. 

Tougher Bugs 

In the age-old battle between men and insects, man has 
devoted his efforts to new and better ways to kill, and the 
insects have retaliated not only by an all-out breeding pro- 
gram, but also by breeding tougher individuals. This goes 
back to Darwin's idea of the survival of the fittest. When 
we use an insecticide, the more susceptible individuals are 
killed off, but some of the real tough babies survive, and 
their offspring, according to the universal law of heredity, 
are tough like their parents. 

This is very disturbing. And it is probably even more 
disturbing in the field of medicine than it is in the field of in- 
secticides. Penicillin, a few years ago, was the "wonder 
drug" — cases of gonorrhea, certain types of pneumonia, and 
many other diseases were cleared up in a short time when 
penicillin was brought into the battle. But before long 
something began to happen: many diseases were no longer 
responding to penicillin treatment the way they formerly did. 
What was happening? Seemingly, the good old law of the 
survival of the fittest. Penicillin killed a lot of germs, but 
a small percentage of germs were not killed, and from these 
penicillin-resistant individuals, new and tougher strains were 

Pencillin is not the only drug with which this phenome- 
non has been noticed. The sulfa drugs, remarkably effec- 
tive at first, began to lose their effectiveness as sulfa-resisting 
strains developed from the germs that survived sulfa treat- 
ment. This, undoubtedly, has happened with all of man's 

*Old Mother Nature 143 

germ killers. The battle never ends. A new drug is de- 
veloped and proves effective for a while. But then strains 
of germs resistant to that drug evolve, and a new drug must 
be found. Who will win the battle — man or germs? It 
is still anyone's guess. Perhaps with our more-or-less indis- 
criminate use of drugs we are merely accelerating the devel- 
opment of tougher and tougher strains of germs — strains 
which will prove resistant to any of our drugs. 

Will the use of DDT result in the development of 
tougher insects? Will the flies and mosquitoes of tomorrow 
walk over a DDT-covered surface or fly through a mist of 
DDT spray with no ill effects? We'll just have to wait and 

Chapter Seven 

The End of the Story 

What Next? 

A.ND there it is — DDT — one of the new- 
est, and certainly one of the most important of the insect kill- 
ers that man has developed for use against his insect enemies. 
Is it the final weapon — the weapon that will win the war for 
mankind? Certainly not! No one claims that it is! 
Against many insects it is ineffective. Against many others 
it is less effective than other insecticides already in use. But 
against many of our obnoxious insea enemies it is the most 
effective substance yet developed. When properly formu- 
lated and applied, DDT will protect man against lice, his dog 
against fleas and ticks, his cattle against flies, and his crops 
and trees against a variety of insects that crawl and fly; it 
will rid his home of flies and mosquitoes; and it will keep his 
bed free from bedbugs. Yes, it will do all of these things — 
and it will do many more. 

But, does this mean that with the advent of DDT these 
insects are doomed to extinction? Can man look forward 
to an insect-free world? Hardly! Insects have existed for 
millions of years, and they have shown remarkable ability to 
adjust themselves to new conditions. Otherwise they could 
not have survived. The development of new poisons for the 
control of insects is usually followed shortly thereafter by 
the appearance of more resistant strains. And when certain 


The End of the Story 145 

insects are driven from a locality, others, perhaps even new 
species, come in to take their place. 

The early, over-optimistic pictures painted by some of 
the more sensational journalists when DDT first made its ap- 
pearance were often based on wishful thinking, not upon 
facts. Because beachheads could be freed from mosquitoes 
before the landing of troops, and practically all insect life 
could be killed on small Pacific islands, people began to 
dream of an insect-free world. One large area after an- 
other was treated with DDT and trillions of insects — both 
good and bad — perished in this mass experimentation. Yet, 
the insects came back. Intoxicating hopes gave way to a de- 
pressing morning-after feeling. Those who were most loud 
in their heralding of the "Miracle" inseaicide, were the first 
to swing in the opposite direaion and belittle the value of 
the material whose praises they had formerly sung. 

Thus again, we saw a repetition of the common cycle of 
events that has accompanied the discovery of every cure for 
the ills of mankind. A few years ago sulfa drugs were hailed 
as the wonder healers for which the world had so long been 
waiting. These drugs were to wipe out all of the diseases 
of man — at least according to the words of many uninformed 
prophets. And then came penicillin to capture the head- 
lines of our papers and the hopes of the ill. Then came other 
drugs, such as gramacidin and streptomycin — and still the 
magic cure-all remains to be found. All of these drugs have 
certain uses and all have certain limitations. The men who 
knew most about them were most conservative in their pre- 
dictions. They were not responsible for the many rash state- 
ments that the public so easily swallowed. 

It is the same with DDT. Yes, it is a magic killer! 
But it is not the silver bullet which will put an end to all in- 

146 DDT— Killer of Killers 

sea life — if that were desirable. And, as in the case of 
the medicinals, those who had the most to do with the de- 
velopment of DDT insecticides were not the ones who made 
the fantastic claims. 

Let us evaluate DDT on the basis of what it has done 
and what it can do — not on what somebody hoped it would 
do. When we take this rational point of view we are led, 
inevitably, to the conclusion that the development of DDT 
was the greatest contribution to the field of insecticides since 
that day in 1869 when man first began to use poisons in his 
fight against his eternal enemies — the enemies that fly, that 
crawl, and that hop; and yet are so small that it is hard for us 
to believe that some day they may, if we weaken our guard, 
inherit the earth. 


JTOR those of you who are too lazy to read 
what we have said in the first part of this book and want to 
get information the easy way, we have added a few pages to 
give you, in condensed form, instruaions on how to use 
DDT for the control of the common insect pests that affect 
man and animals. 

And for the benefit of gardeners, farmers, foresters, and 
nature-lovers in general, we have included information on 
how to use DDT to control the more common insea pests 
that affect agricultural crops and forest and shade trees. 

We realize that the second part of the Appendix is 
not as extensive as it might be, and we don't want you tillers 
of the soil to feel that we have slighted you. The reason 
that this section is not longer is due merely to the faa that 
DDT is so new that our agriculturists have not had time to 
make the extensive tests that are necessary before an inseai- 
cide can be recommended for all the uses to which it can 
probably be put. Perhaps at some later date we may be 
able to bring you the whole story, but for the time being this 
will have to do. 



Instructions for the use of DDT in the con- 
trol of the common insect pests that affect 
man and animals. 

Appendix 151 


For the control of ants in buildings, apply a 5 % DDT 
solution, by spray or brush, behind and beneath baseboards, 
window sills and frames; around sinks, and table and chair 
legs; to both sides of pantry shelves; and to cracks and crev- 
ices leading to the outside of the building. If the ants travel 
along well-defined trails, pay particular attention to these 
areas. A 10% powder is also effective, but is usually more 
difficult to apply and, of course, leaves a visible deposit. How- 
ever, the powder is very effeaive when applied directly to ant 
hills. Ants will usually abandon an ant hill within a short 
time after a small amount of DDT powder is applied around 
the entrance holes. 

A single application of the spray or powder will control 
many species of ants for several weeks. However, some 
species do not respond to the DDT treatment. In such cases, 
the addition of /4o% pyrethrins to the 10% powder often 
proves effeaive. 


DDT is the perfect answer to bedbug control. Three 
fluid ounces of 5 % DDT in deodorized kerosene, used as a 
spray, or about 2 oz. avdp. of a 10% DDT powder will not 
only kill all the bedbugs in a full-sized bed, but will prevent 
re-infestation for at least 6 months. The spray or powder 
should be applied to both sides of the mattresses and pillows, 
to the bed springs, and to the cracks and joints in the bed- 
steads. Furthermore, since bedbugs may hide behind pic- 
tures on walls, and in cracks and crevices along the window 
and door frames and along baseboards and mouldings, these 
places should also be sprayed or dusted. When the spray 

152 DDT— Killer of Killers 

is used, the bed should be permitted to dry for a few hours 
before it is made up. Neither the DDT dust nor the DDT 
deposit lek after the evaporation of the solvent from a spray 
will harm the skin. 


For the control of carpet beetles in carpets, rugs, and up- 
holstered furniture, treat with a 5 % DDT solution in the 
same manner as described for the control of clothes moths. 


(See MOTHS) 


DDT is effective for the control of the American cock- 
roach, the German cockroach, and the brown-banded roach. 
Either 5 % DDT in kerosene or in emulsion form or a 10% 
DDT powder can be used for the control of these insects. 
With either material, it is necessary to maintain an effective 
residual deposit. To kill roaches as they come into the 
building from the outside, or as they migrate from one part 
of the building to another, apply the spray or powder to 
their hiding places — around refrigerators and sinks; pantry 
shelves, table tops, table and cupboard drawers, and pipe 
openings; and along baseboards, cracks, mouldings, etc. Since 
cockroaches like to walk upside down beneath refrigerators, 
shelves, and table tops, it is a good idea to spray these places 

The action of DDT on roaches is slow, but it eradicates 
an infestation in about a week after application if the DDT 
residue is not removed. 

Appendix 153 




For fleas on dogs, dust a 10% DDT powder thoroughly 
into the hair of the animal, along the back from the head to 
the tail. About 1 tablespoon of powder is sufiicient for the 
average-sized dog. For perhaps an hour after application, 
fleas will probably show greater activity with resultant great- 
er discomfort to the animal; however, the fleas begin to die 
in about 10 minutes, and after a few hours none are left. A 
single treatment is sufficient to protea dogs from further in- 
festation for several days. 

In addition to dusting the animal, treat the sleeping 
places of the dog, and infested basements and rat burrows 
with about % lb. of 10% DDT powder or /4 gallon of 5 % 
DDT solution per 1,000 square feet of floor space. 

For flea-infested floors, rugs, overstuffed furniture, and 
fabrics, a light application of about 1 gallon of 5 % DDT 
in kerosene per 4,000 square feet of surface is not only ef- 
fective against the fleas themselves but also against the flea 
larvae. A 5 % DDT emulsion or a 2 % % DDT suspension 
of wettable powder can be used in place of the kerosene 
spray where staining and the white residue are not objec- 
tionable. DDT suspensions are particularly advantageous 
for use on flea-infested lawns, where kerosene might damage 
the grass. 

For the control of fleas on cats, DDT powder should not 
be applied directly to the animal since cats lick themselves 
and might ingest sufficient DDT to make them sick. How- 
ever, treatment of the sleeping places of cats and other flea- 

154 DDT — Killer of Killers 

infested areas, as described above, is very effective for con- 
trolling fleas. 

In Buildings 

Space sprays with as little as % % DDT, together with 
pyrethrum or organic thiocyanates for rapid knockdown, will 
kill all flies that are hit by the spray mist. 

Aerosols containing 3 % DDT and 2 % pyrethrum ex 
tract are very Q^Gcdwt space sprays. The extremely fine mist 
that is evolved while the trigger is depressed remains in sus- 
pension for a considerable period of time and is carried to all 
parts of the room. 

Residual sprays containing 5 % DDT in deodorized 
kerosene are used where long-lasting action is desired. These 
sprays are applied to the walls and ceilings, screen doors, 
lamp cords, and other surfaces on which insects light. An 
invisible deposit of DDT remains after the evaporation of 
the solvent, and any insects that come in contact with it are 
doomed, although they may continue to live for an hour or 
more. The spray should be applied at the rate of 1 quart 
for every 250 square feet of surface. One application will 
remain effective for long periods of time — from a few weeks 
in exposed places up to several months in enclosed areas. 

Emulstfiahle solutions of 25 or 30% DDT can also be 
used where residual action is desired. These solutions are 
mixed with water before use to provide an emulsion of 5 % 
DDT. These emulsions, however, should not be used where 
water might stain the surface or where the white deposit is un- 
sightly. For use in barns and other outbuildings where 
staining and appearance are not faaors that have to be con- 

Appendix 155 

sidered, emulsions are desirable since they eliminate the fire 
hazard associated with an oil spray. 

Wettahle powders containing up to 50% DDT mixed 
with pyrophyllite make effective residual sprays for barns 
and other outbuildings where one doesn't mind the white 
deposit on the walls. For use, sufficient powder is added to 
water to giYQ a 2% % DDT mixture. A 5 % mixture is not 
needed because the powder, unlike the oil solutions and 
emulsions, does not penetrate into porous surfaces. About 
1 gallon of the 2% % spray should be used for approximate- 
ly 300 square feet of surface. 

Paints containing up to 6% DDT are available, and 
can be used where residual aaion is desired. They afford 
protection for approximately the same length of time as the 
usual types of residual sprays. 

On Cattle and Horses 

For the control of houseflies, stable flies, and horn flies 
on cattle or horses use a 2 /4 % DDT emulsion or dispersion 
of wettable powder. Apply the spray at the rate of about 1 
quart per adult animal, paying particular attention to the 
belly, rump, and back. A single application should effec- 
tively control the flies for at least 2 weeks. An alternative 
method is to dip the animal in an emulsion of about % % 
DDT. On the average, about 2 gallons are required for 
each adult animal. 


( See WASPS and hornets ) 

On Humans 

There are three types of lice that affea humans: body 

156 DDT — ^Killer of Killers 

lice, head lice, and crab, or pubic, lice. DDT 'is effeaive 
against all three types. 

For the body louse, apply 1 ounce of 10% DDT pow- 
der to the inner surface of underclothing and another % 
ounce to the seams of the outer garments. A single applica- 
tion will completely eradicate the lice, and if left in the cloth- 
ing the powder will continue to kill lice for several months. 

For the head louse, thoroughly shake a 10% DDT pow- 
der into the hair. It will kill all lice but will not kill the 
eggs, or nits. Since it takes several days for the eggs to 
hatch, the DDT powder should be left in the hair for at 
least 10 days in order to kill the young lice as they hatch 
from the eggs. An alternative method is to make two ap- 
plications of the DDT powder about 8 to 10 days apart. 
It is advisable to let each application remain for about 24 
hours before washing the hair. The second application will 
kill lice that have hatched since the first application was 

In order to get rid of head lice in a hurry, the NBIN 
formula can be used since it kills the eggs as well as the adult 
lice. This material is applied to the hair in the form of an 
emulsion made up of 5 parts of water and 1 part of a con- 
centrate consisting of 68 parts of benzyl benzoate, 12 parts of 
benzocaine, 6 parts of DDT, and 14 parts of a dispersing 
agent. The hair should be thoroughly wetted with the emul- 
sion, combed to insure uniform distribution, and then per- 
mitted to dry. It is unnoticeable in the hair, and should be 
left on for 8 to 10 days in order to kill any lice that may 
have been hiding in the clothing and ultimately return to 
the head. 

The crab, or pubic, louse can also be killed with either 
a 10% DDT powder or an emulsion of the NBIN formula. 

Appendix 157 

In either case, the material should be applied to all hairy 
portions of the body, including the arm pits, chest, the pubic 
and perineal region, and the legs, and should be thoroughly 
rubbed in with the fingers. A single application of the 
NBIN formula, left on for 24 hours in order to catch any 
lice that have been hiding out in the bedding or clothing, 
will completely eradicate the infestation. If the powder is 
used, it should be left on for 24 hours before one takes a 
bath, and a second application should be made in about 8 
or 10 days. 

On Cattle 

Apply 10% DDT powder to infested cattle, either by 
dusting or by rubbing the powder into the coat by hand. Pay 
particular attention to the neck, ears, head, shoulders, with- 
ers, tail base, and inner leg surfaces. An alternative method, 
which is particularly advantageous when a large number of 
animals are to be treated, is to dip the animals in an emul- 
sion or dispersion of about % % DDT in water. Emulsions 
are readily prepared from solutions of 25 or 30% DDT in 
soluble pine oil or other solvent, and dispersions are easily 
made by adding about 30 pounds of 50% DDT wettable 
powder to 1,000 gallons of water. 

On Coats, Hogs, etc. 

A % % DDT dip, as described above, will satisf aaorily 
control lice on goats, hogs, and other animals as well as on 

On Poultry 

Dust either a 5 or 10% DDT powder well into the 
feathers of the birds, getting it down to or near the skin sur- 

158 DDT— Killer of Killers 

face. Pay particular attention to the head and neck, under- 
neath the wings, and below the vent. 

In Homes 

Mosquitoes in homes can be killed with the same DDT 
formulations that are used against flies. Space sprays can 
be used to kill the mosquitoes present at a given time, or 
residual sprays — oil sprays, emulsions, or dispersions of wet- 
table powders — can be used to kill mosquitoes that venture 
around the premises over a period of months. 

Around Premises 

To cut down the mosquito population, it is also a good 
idea to either spray the lawn and shrubbery around the house 
with a 2 /4 or 5 % DDT emulsion or dispersion, or to sprinkle 
them with a 5 or 10% DDT powder. 

In Breeding Grounds 

For effective mosquito control, the breeding grounds 
should be treated with about /4o pound of DDT per acre. 
The DDT can be applied in the form of a kerosene or other 
oil solution, as an emulsion, or as a dispersion of wettable 
powder in water. For large areas of swampland or vege- 
tation, application by airplane is very effeaive. For stag- 
nant waters, 1 part of DDT per 100,000,000 parts of water 
will kill the larvae of most species of mosquitoes. 

in Cloriies 

DDT is very effective against both the adult moth and 

Appendix 159 

the larvae. One application protects clothes from moths for 
several months if the residue is not removed by dry clean- 
ing. For application to clothes and upholstery, 5 % DDT 
in deodorized kerosene may be used, but a more volatile sol- 
vent such as dry-cleaner's solvent (Stoddard solvent) is pref- 

For clothes hanging in closets, spray the garments 
liberally, paying particular attention to the seams and folds, 
and also apply a thorough deposit to the closet walls, ceiling, 
and floors, and especially to cracks and openings around the 

In Stored Woolens 

For woolens that are to be stored in chests, first spray 
the chest thoroughly with a 5 % DDT solution, and then 
spray each garment as it is put away. Apply the spray to all 
surfaces of the goods, paying particular attention to seams 
and folds. 

In Carpets, Rugs, and Upholstered Furniture 

For carpets, rugs, and upholstered furniture, spray the 
surfaces of the articles liberally with a 5 % DDT solution. 
In the case of upholstered furniture, also either inject a spray 
needle into the furniture padding so as to obtain more ef- 
fective application, or else remove the backing and spray the 
padding. This treatment will also protea rugs, carpets, and 
upholstered furniture against carpet beetles. 


Treat the breeding places of these insects with 5% 
DDT solution or 10% powder. Likely areas are behind 

160 DDT— Killer of Killers 

loose wall paper and in or near bookcases, and particularly 
in basements near furnaces and other warm locations. 


Treat the soil around the timbers that are to be pro- 
tected with a 5 % DDT-kerosene solution. One treatment 
will remain effective for at least two seasons. 

Brown Dog Tick 

About the only tick found in large numbers in homes 
is the brown dog tick. This tick hides in cracks and crevices 
about baseboards, and in floor coverings. After getting their 
meal of blood from dogs or other animals, the ticks return 
to their hiding places. 

Treatment of dogs and the building premises with 10% 
DDT powder for eradication of fleas, as described previously, 
will effeaively control this tick. However, DDT kills the 
tick slowly, and powder sprinkled around the floors should 
be permitted to remain for about 2 weeks. Although it 
cannot be used on the animals themselves, a 5 % DDT-kero- 
sene spray is very effective against the brown dog tick when 
applied to walls, floors, rugs and other hiding places of the 

Fowl Ticks 

Poultry houses infested with fowl ticks can be success- 
fully treated with 5 % DDT in kerosene. The perch poles, 
cracks and crevices, behind and beneath nesting boxes, and 
other potential hiding places of the tick should be thorough- 

Appendix 161 

ly sprayed. A single application will keep the poultry house 
free from ticks for 3 months or longer, and at the same time 
will eradicate poultry mites. Obviously, to avoid any pos- 
sible injury to the poultry, spraying should be done when the 
birds are not in the house. 

American Dog Tick 

This tick, which can transmit the eastern strain of 
spotted fever, is often found in parks, camp sites, and on 
the premises of residences. It can be controlled by apply- 
ing a % % DDT emulsion at the rate of about 3 pounds of 
DDT per acre. 


These inseas are killed readily by DDT. Spray their 
nests with 5 % DDT solution or dust them with 10% pow- 
der, and the wasps or hornets will abandon their nests with- 
in a very short time. 

Part II 

Instructions for the nse of DDT on vege- 
tables, flowers, and shade and forest trees. 

Appendix 165 


Lygus Bug Control 

Apply, just before bloom, a 5% DDT-sulfur dust at 
the rate of 30-40 pounds per acre, or a 10 % DDT dust at the 
rate of 15-20 pounds per acre. 

Leaf Hopper and Leaf Roller Control 

Apply a 3 % DDT dust at the rate of 30-40 pounds per 
acre every 2 or 3 weeks before the pods are formed. 


Cabbage Worm, Cabbage Looper, and Diamond -Back Moth 

Apply a 2 or 3 % DDT dust at the rate of 20-30 pounds 
per acre every 2 or 3 weeks before the heads form, or apply 
150 gal. per acre of a spray prepared from 1 pound of 50% 
DDT wettable powder per 100 gal. of water. Make the 
first spraying a week or 10 days after the plants are set; the 
second application 2 to 3 weeks later as needed; and the third 
application about the time the heads start to form. 

Do not apply DDT for 30 days before cabbage is to be 
ready for market. 


Thrip Control 

Apply a 3% DDT-sulfur dust at the rate of 125-150 
pounds per acre when infestation occurs, or apply 100 gal. 

166 DDT — ^Killer of Killers 

per acre of a spray prepared from 4 pounds of 50% DDT 
wettable powder per 100 gal. of water. 


European Corn Borer Control 

Use either a 3 % DDT dust or a spray prepared from 
DDT wettable powder. The 3 % dust is applied at the rate 
of 30-40 pounds per acre at weekly intervals just before the 
tassels emerge. The spray is prepared from 1 pound of 50 % 
DDT powder per 100 gal. of water, and is applied at the rate 
of 150-200 gal. per acre. Three to five applications should 
be made at 5- to 7-day intervals. 


Boll Worm Control 

Apply a 5 % DDT dust at the rate of 15-20 pounds per 
acre as soon as the moths begin laying eggs. Make 2 or 3 
applications at 5 -day intervals. 

Flea Hopper and Lygus Bug Control 

Apply a 5 % DDT-sulfur dust at the rate of 25 pounds 
per acre as soon as infestation appears. 


Thrip and Aphid Control 

DDT gives very good control of thrips and aphids on 
snapdragons, chrysanthemums, and roses. A satisfactory 
spray can be prepared by adding 1 to 2 pints of 25 % DDT 
emulsifiable solution to 100 gallons of water. Application 

Appendix 167 

should be made about every 2 or 3 weeks, or as often as the 
inseas reappear. 


(See TREES) 

Leaf Hopper Control 

Apply a straight 3 % DDT dust or a 3 % DDT-sulf ur 
dust at the rate of 20-30 pounds per acre before the fruit sets. 
An alternative procedure is to use an atomized oil spray con- 
sisting of 1-2% DDT in kerosene or mineral seal oil. The 
spray should be applied at the rate of 2-4 gal. per acre as 
soon as the leaf hopper appears and before the fruit has set. 

Thrip Control 

Use either a 3 % DDT dust or a spray of DDT wettable 
powder. Apply the dust at the rate of 45-50 pounds per 
acre at the first sign of thrip damage, and repeat this treat- 
ment at 1 4-day intervals as needed. Prepare the spray by 
using 1 to 2 pounds of 50% DDT wettable powder per 100 
gal. of water, and apply at the rate of 200 gal. per acre. 
Make 2 or 3 applications at intervals of 10-14 days apart 
after thrips appear. 

Aphid Control 

Apply a 4 or 5 % DDT dust at the rate of 35-40 pounds 
per acre when aphids begin to appear in numbers. 

168 DDT — Killer of Killers 

Weevil Control 

Apply 5 % DDT dust at the rate of about 20 pounds 
per acre after weevils appear but before the pods are formed. 


Colorado Potato Beetle Control 

Apply a 2 or 3 % DDT dust, with or without fungicides, 
at the rate of 20-30 pounds per acre when the plants are 
6 to 8 inches high, or apply a spray made from 1 pound of 
50% DDT wettable powder per 100 gal. of water at the 
rate of 100-150 gal. per acre. 

Leaf Hopper and Potato Flea Beetle Control * 

Apply a 3% DDT-copper dust at the rate of 30-40 
pounds per acre as soon as the pests appear, and repeat at 
10- to 14-day intervals as needed. Or, spray with a suspen- 
sion prepared from 2 pounds of 50% DDT wettable pow- 
der per 100 gal. of water. 

Psyllid and Tuber Flea Beetle Control 

Use a 5 % DDT-sulfur dust at the rate of 20 pounds 
per acre, or a 3 % DDT dust at the rate of 35-40 pounds per 
acre as soon as insects appear, and repeat every 10-14 days 
as needed. A spray prepared from 2 pounds of 50% DDT 
wettable powder per 100 gal. of water can also be used. 

Aphid Control 

Apply a 5% DDT-copper dust at the rate of 40-45 
pounds per acre every 10 days starting with the first appear- 
ance of the aphids. 

Appendix 169 


{See trees) 


Lygus Bug Control 

Apply a 5% DDT-sulfur dust at the rate of 30-40 
pounds per acre, or a 10% DDT dust at the rate of 15-20 
pounds per acre. 


Shade Trees 

Apply a /4o % emulsion with a hand knapsack or pow- 
er sprayer until the spray material begins to run from the 
surfaces of the leaves. This will give excellent control 
against defoliating insects, such as the gypsy moth, elm leaf 
beetle, catalpa caterpillar, locust leaf miner, boxwood leaf 
miner, canker worm, sawfly, evergreen bagworm, tent cater- 
pillar, and many others. 

Forest Trees 

Defoliating insects on forest trees can be controlled in 
the same manner as described above for shade trees, but this 
method is satisfactory for only relatively small areas. For 
large tracts of forest lands, the only practical method is to 
spray the area from an airplane. 

The quantity of DDT required is usually from about 
■!4 to 1 pound per acre. Since fish are much more susceptible 
to DDT poisoning than are warm-blooded animals, the 
amount of DDT applied over areas containing fishing streams 
should not exceed V4. pound per acre. 

170 DDT— Killer of Killers 

The DDT can be applied in the form of an emulsion 
or as a dispersion of wettable powder, but the most common 
spray solution is prepared by dissolving DDT in xylene and 
diluting this solution with fuel oil to a concentration of about 
10 or 12% DDT. 


Active ingredients, 74 
Aedes aegypti, 22, 112 
Aerosols, 68, 80, 154 

bombs, method of using, 76, 77, 

Africa, yellow fever in, 22 
African sleeping sickness, 28 
Agricultural crops, destruction of, by 

insects, 3 
use of DDT on, 129, 163 
Agricultural dusts, DDT, 69, 88, 165 
Alfalfa, control of insects on, 141, 

American dog tick, control of, 127, 

American Medical Association, 45 
American Typhus Commission, 2 
Annand, P. N., 3 
Anopheles, 15, 80, 112 
Ants, 120 

control of, 85, 122, 151 
Aphids, control of, 166, 167, 168 
Army Medical Service, 22 
Arsenic, 63 
Atebrin, 20 
Australia, encephalitis epidemic in, 



Balance of nature, 137 

Beans, control of insects on, 165 

Bedbugs, 101 

control of, 85, 102, 151 
Bees, 139 

effect of DDT on, 140 

Beetles, control of, 168 

Berichte der Chemischen Gezell- 

schaft, 30 
Birds, as reservoir of encephalitis, 28 

effect of DDT on, 61 
Bishop, F. C, 34 
Black Death, 5 

loss of life from, 6 
Body lice, 91 

control of, 92, 156 
Boll worm, control of, on cotton, 

Boxwood leaf miner, 169 
British Indian Plague Commission, 8 
British Ministry of Supply, 40 
Brown dog tick, control of, 127, 160 
Brown-tail moth, 134 
Brussels, plague epidemic in, 6 
Bubonic plague, 5 
Bulgaria, typhus epidemic in, 14 
Burns, Robert, 91 
Butterflies, 130 

Cabbage, control of insects on, 165 
Cabbage looper, control of, 165 
Cabbage worm, control of, 165 
California, plague epidemic in, 7 

University of, 28 
Camp fever, 10 
Canker worm, control of, 169 
Caribbean, 23 

Carpet beetles, control of, 152 
Carpets, protection of, against moths, 

Casualties of World War 11, 4 




Catalpa caterpillar, control of, 169 
Caterpillars, 130 

control of, 132, 169 
Cattle, control of flies on, 111, 118, 

136, 155 
control of lice on, 157 
dips. 111, 155 
Central powers, 14 
Charles V, 12 
Charleston, yellow fever epidemic in, 

Chipmunks, as reservoirs of plague, 9 
Cholera during Crimean War, 13 
Chloral hydrate, 31, 40 
Chlorobenzene, 31, 40 
Chovis, 87 

Cimex lectularius, 102 
Cinchona, 19 

Cincinnati Chemical Works, 39 
Citrus fruits, control of insects on, 

Civil War, malaria victims during, 

Cleanliness, role of, in typhus con- 
trol, 11 
Qement VII, 12 
Clothes, protection of, against moths, 

132, 158 
Cockroaches, control of, 85, 152 
Colorado potato beetle, control of, 

33, 129. 168 
Commercial Standard CS72-38, 72 
Constance, plague epidemic in, 6 
Constantinople, plague epidemic in, 

Contact poisons, 62 
Corn, control of insects on, 166 
Corn borers, control of, 166 
Cotton, control of insects on, 166 
Crab lice, control of, 101, 156 
Craft, Willis, 78 

Crimean War, 13 

Crops, agricultural, magnitude of 
destruction by insects, 3 

control of insects on, 129, 163 
Crusaders, 16 
Cuba, 23, 24 

yellow fever epidemic in, 23 
Culex, 112 
Culicidae, 112 
Culicinae, 112 

Dalmatia, plague epidemic in, 5 
Danger in use of DDT, 47 
DDT, aerosols, 68, 80, 154 

agriculmral dusts, 69, 88, 165 

composition of, 40 

dips, for control of flies on cattle, 
111, 155 

discovery of, 30 

dusts, 69, 88, 165 

emulsions, 68, 85, 87, 154, 156 
for use on plants, 87 

formula of, 40 

formulations, 67 

in paints, 69, 89, 155 

jitters, 64 

mechanism of poisoning by, 62, 64 

patents, 39, 40 

powders, 2, 68, 84, 87, 122, 125, 

preparation of, 31, 40 

production of, 41 

properties of, 41, 42 

residual sprays, 6G, 82, 154 

safety precautions in use of, 47 

solutions, eff^ea of, on skin, 52 

sprays, 68, 79, 81, 154, 159 
toxicity of, 51 

tremors, AA, 64 



toxicity of, 44, 47, 52 

to birds, 61 

to fish, 61 

to inseas, 66 

to man, 44, 47, 52 

to warm-blooded animals, 48, 
wettable powders, 68, 87, 155 
DDT for control of, American dog 
tick, 127, 161 
ants, 85, 122, 151 
aphids, 166, 167, 168 
bedbugs, 85, 102, 151 
beetles, 168 
body lice, 2, 92, 156 
boll worms, 166 
boxwood leaf miners, 169 
brown dog ticks, 127, l60 
cabbage loopers, l65 
cabbage worms, 165 
canker worms, l69 
carpet beetles, 152 
catalpa caterpillars, l69 
clothes moths, 132, 158 
cockroaches, 85, 152 
Colorado potato beetles, 33, 168 
corn borers, l66 
crab lice, 101, 156 
defoliating inseas, 169 
diamond-back moths, l65 
dog fleas, 85, 125, 153 
dog ticks, 127, 160 
elm leaf beetles, 169 
evergreen bagworms, l69 
insects that affect man and ani- 
mals, 149 
firebrats, 159 
flea hoppers, 166 
fleas, 85, 125, 153 
flies, in barns, outbuildings, etc., 
107, 111, 154 

in dairies. 111 

in homes, 68, 69, 154 

on cattle and horses. 111, 155 
forest insect pests, 134, 169 
gypsy moths, 62, 132, 134, 169 
head lice, 99, 156 
horn flies, HI, 155 
hornets, l6l 
insects on, alfalfa, l65 

beans, 165 

cabbage, 165 

citrus fruits, 165 

corn, 166 

cotton, 166 

flowers, 166 

forest trees, 169 

grapes, 167 

onions, 167 

peas, 167 

potatoes, 168 

shade trees, 169 

sugar beets, 169 
lice, on cattle, 157 

on goats and hogs, 157 

on humans, 101, 155 

on poultry, 157 
leaf hoppers, 165, 167, 168 
leaf rollers, 165 
locust leaf miners, 169 
lygus bugs, 165, 166, 169 
mosquitoes, 113, 119, 158 

around premises, 158 

in breeding grounds, 120, 158 

in homes, 114, 158 
moths, 132, 158 

in carpets, 159 

in clothes, 158 

in rugs, 159 

in stored woolens, 159 

in upholstered furniture, 159 
potato flea beetles, 168 



psyUids, 168 
roaches, 85, 152 
sawflies, 169 
silverfish, 159 
tent caterpillars, 132, 169 
termites, 124, 160 
thrips, 166, 167 
ticks, 127, 160 

American dog, 127, l6l 
brown dog, 127, 160 
fowl, 128, 160 
tuber flea beetles, 168 
wasps, l6l 
weevils, 168 
Darwin, 142 

Deaths, due to, bubonic plague, 6, 9 
poliomyelitis, 106 
spotted fever, 27 
typhus, 11-14 
yellow fever, 23 
in World War II, 4 
Defoliating insects, control of, 169 
De Jonge, Major, 33 
Dengue, 113, 120 
Destruction of agricultural crops by 

insects, 3 
Diamond-back moth, control of, 165 

Dips, for cattle, 111, 157 
for goats, 157 
for hogs, 157 
for sheep, 88 
Dog ticks, control of, 127, 160 
Dove, W. E., 34 
Du Pont Co., 39, 131 
Djsts, agricultural, 69, 88, 165 
Dutch elm disease, 133 
Dysentery, 13, 26, 104 
during Crimean War, 13 

Edison, Thomas, 74 

Elm leaf beetle, control of, 169 

Emulfor, 87 

Emulsifying agents, 86, 87 

Emulsions, 86 

of DDT, 68, 86, 87, 154, 156 
Encephalitis epidemics, 28 
England, plague epidemic in, 5 
English sparrow, 137 
Epidemics of, encephalitis, 27 

malaria, 16 

plague, 5-10, 12 

poliomyelitis, 26, 106 

typhus, 1, 11-14 

yellow fever, 22 
Europe, plague epidemic in, 5, 

encephalitis, epidemic in, 28 

typhus epidemics in, 11-14 
Evergreen bagworm, 169 

Ferdinand and Isabella, 11 
Fever, camp, 10 

jail, 10 

ship, 10 

spotted, 10 

typhoid, 25 
Filariasis, 113 
Firebrats, control of, 159 
Fish, effect of DDT on, 61 
Flea hopper, control of, 166 
Fleas, 124 

as carriers of plague, 7, 124 

control of, 85, 124, 153 
Flies, 103, 110 

control of, 107, 154 
in barns, 107, 111, 154 
in buildings, 154 
in dairies, 110 



on cattle and horses, 110, 111, 

on Mackinac Island, 109 
on manure piles, 107 
horn, 110 

control of. 111, 155 
house, 110 

control of. 111, 154 
role of, in transmission of, in- 
testinal flu, 26, 104 
pink eye, 27 
poliomyelitis, 26, 105 
stable, 110, 155 
tsetse, 28 
Florence, plague epidemic in, 6 
Flowers, control of insects on, 166 
Forest insect pests, control of, 62, 

Forest trees, control of insects on, 

134, 169 
Formula of DDT, 40 
Formulations of DDT, 67 
Fowl tick, control of, 160 
Fox, General Leon, 2 
France, plague epidemic in, 5 
Francis I, 12 
Freon, 81 

Fruits, control of insects on, 165 
Fuel oil in insect sprays, 79 

Galveston, yellow fever epidemic in, 

Geigy Company, Inc., 34, 39 
Geigy DDT patent, 39, 40 
Geigy, J. R., A. G., 32 
General Motors Corp., 81 
Genoa, plague epidemic in, 5 
German Empire, 12 
Germany, plague epidemic in, 6 
Gesarol, 33 

Goats, control of lice on, 157 

Grade A, 73 

Grade AA, 71 

Grade B, 73 

Gramacidin, 145 

Granada, seige of, 11 

Grapes, control of insects on, 167 

Great Britain, encephalitis epidemic 

in, 28 
Greece, malaria in, 16 

plague epidemic in, 5 

typhus epidemic in, 14 
Greek civilization, effect of malaria 

on, 16 
Greeks, campaign of, against Egyp- 
tians, 16 
Greenland, plague epidemic in, 6 
Ground squirrels as reservoirs of 

plague, 9 
Gypsy moth, 62, 132, 134, 137, 169 


Haiti, Republic of, 23 
Haladay, E. J., 77 
Hammon, W. H., 28 
Hannibal, 16 
Hasskarl, 20 
Head lice, 91, 93 

control of, 99, 156 
Helena, Arkansas, 114 
Hemlock looper, 62, 134 
Hercules Powder Co., 39 
Hill, Arthur W., 36 
Hitler, Adolf, 128 
Hog dips, 88 
Hogs, control of flies on, 123 

control of lice on, 157 
Honeybees, 139 

effea of DDT on, 140 
Hong Kong, plague epidemic in, 7 
Hooper Foundation, 78 



Horn fly, 110 

control of, HI, 136, 155 
Hornets, control of, 16 1 
Horses, control of insects on, 155 

encephalitis in, 28 
Houseflies, 110 

control of. Ill, 154 
Household sprays, 69, 151 

testing of, 71 
Howard, L. O., 3 


Iceland, plague epidemic in, 6 
Imperial Army, 12 
India, plague epidemic in, 7 
Insect sprays, 69, 151 

testing of, 71 
Insecticides, types of, 62 
Insects {see also ants, fleas, flies, lice, 
destruction of agriculmral crops 

by, 3 
role of, in transmission of disease, 
Instructions for use of DDT on in- 
sects that affect, man and ani- 
mals, 149 
plants, 163 
Intestinal flu, 26, 104 

role of fly in transmission of, 26, 
Ireland, plague epidemic in, 5 
Italy, fate of, decided by typhus, 12 
plague epidemic in, 5 
typhus epidemic stopped in, 2 


Jail fever, 10 

Japan, encephalitis epidemic in, 28 

Java, cinchona plantations in, 20, 

Jellison, W. L., 27 

Jews, persecution of, 8 
Justinian I, 5 

Kerosene, definition of, 74 

in insect sprays, 75 
Kissinger, John R., 22 
Knipling, E. F., 34 
Knockdown agents, 70 

Lannoy, 12 

Lautrec, 12 

Laveran, 15 

Lazear, Jesse, 22 

Leaf hoppers, control of, 165, 167, 

Leaf roller, control of, 165, 166 
Leclere, .23 
Ledger, Charles, 21 
Lepidoptera, 131 
Lethane, 70 

Limoges, typhus epidemic in, 13 
Lice, 10 

as carriers of typhus, 1, 10, 14 
body, 91, 92, 156 
control of on, cattle, 157 
hogs, 88, 157 
goats, 157 
humans, 155 
poultry, 157 
sheep, 88 
crab, 91, 100 

control of, 101, 156 
head, 91, 93 

control of, 99, 156 
pubic, 91, 100 

control of, 101, 156 
role of, in transmission of typhus, 

1, 10 
types of, 91 



Locust leaf miner, control of, 169 
rOuverture, Toussaint, 23 
Lubeck, plague epidemic in, 6 
Lygus bugs, control of, 165, 166, 169 
Lyons, typhus epidemic in, 13 


Mackinac Island, 108 
Malaria, 15, 19 
deaths from, 16 
during Civil War, 16 
during Spanish- American War, 16 
in Greece, 16 
in the United States, 15 
Malaria-bearing mosquito, 15, 80, 
control of, 19, 113, 114 
Markham, Sir Clements, 20 
Marseilles, plague epidemic in, 5 
Mediterranean basin, 16 
Memphis, yellow fever epidemic in, 

Merck & Co., 39 
Met2, seige of, 12 
Midgley, Thomas, 81 
Monkeys, as reservoirs of yellow 

fever, 24 
Montclair, New Jersey, 133 
Moscow, Napoleon's retreat from, 13 
Mosquitoes, 112 

aedes aegypti, 22, 112 
anopheles, 15, 80, 112 
as carriers of, dengue, 120 
encephalitis, 28 
malaria, 15 
yellow fever, 22 , 
breeding habits of, 19, 24, 113 
control of, 95, 114, 119, 158 
around premises, 158 
by use of airplane, 98 
drip method for, 115 

dusting method for, 116 
in breeding grounds, 120, 158 
in homes, 114, 158 
Culicidae, 112 
Culicinae, 112 
Culex, 112, 113 
types of, 112 
Moths, 130 

control of, diamond-back, 165 
in carpets, 159 
in clothes, 132, 158 
in rugs, 159 
in stored woolens, 159 
in upholstered furniture, 159 
on plants, 132, 165 
Mulag, 87 

Miiller, Paul, 17, 32 
Musca domestica, 103, 104 


Naphthalene, 62 
Naples, 1, 27 

plague epidemic in, 5 

seige of, 12 

typhus epidemic in, 1, 12, 35 
Napoleon, 13, 23 

National Association of Insecticide 
and Disinfectant Mfrs., Inc., 
National Bureau of Standards, 72 
National Institute of Health, 45 
Nature, balance of, 137 
NBIN formula, 100 
Netherlands, plague epidemic in, 6 
New Orleans, yellow fever epidemic 

in, 23 
Nicolle, Charles, 10 
Nightingale, Florence, 13 
Nits, 92 

North America, encephalitis epidem- 
ic in, 28 



Nuttall's cottontail, 27 
Nylon, 131 


Oils for insect sprays, 75 
Onions, control of insects on, 167 

Paints containing DDT, 69, 89, 155 

Panama, 23, 24 

Panama Canal, 23, 114 

Paris, plague epidemic in, 5, 6 

Paul, John R., 106 

Peas, control of insects on, 167 

Pediculus capitis, 91 

Pediculus corporis, 91 

Peet-Grady, chamber, 72, 96, 97 

method, 72 
Penicillin, 142, 145 
Pestroy, 90 
Philadelphia, yellow fever epidemic 

in, 23 
Phthirius pubis, 91 
Pine sawfly, 62, 134 
Pine-tip moth, 62, 134 
Pink eye, 27 
Plague, bubonic, 5 

effect of, on Roman Empire, 5 

epidemics, 5-10, 12 

relationship of rats and fleas in 
transmission of, 7 
Poisons, contact, 62 

respiratory, 62 

stomach, 62 
Poliomyelitis, 104 

epidemics, 26, 106 

role of fly in transmission of, 26, 
Portland, Maine, yellow fever epi- 
demic in, 23 
Potato beetle, Colorado, control of, 
33, 129, 168 

Potato flea beetle, control of, 168 
Potatoes, control of insects on, 168 
Poultry lice, control of, 157 
Prairie dogs, as reservoirs of plague, 

Pretoria, South Africa, 28 
Psyllids, control of, 168 
Pubic louse, 91, 100 

control of, 101, 156 
Pyrethrins, 122 
Pyrethrum, 70, 80, 81, 83 
Pyrophyllite, 68, 85, 88 

Quinine, 15, 19 

Queens, New York, spotted fever 
epidemic in, 27 

Rabbits, as reservoirs of, plague, 9 
spotted fever, 27 
in Australia, 137 
Rats, as reservoirs of, plague, 7 

typhus, 15 
Reed, Walter, 22, 23 
Reeves, W. C, 28 
Residual sprays, 66, 154 
Respiratory poisons, 62 
Ricketts, H. T., 11, 27 
Rickettsiae, 11, 15, 27 
Rio de Janeiro, 24 
Roaches, control of, 85, 152 
Rockford, Illinois, polio epidemic in, 

Rocky Mountain spotted fever, 27, 

Roman Empire, effect of plague on, 5 
Rome, sack of, 12 
Ross, Ronald, 15 
Rotenone, 63 
Rugs, protection of, against moths, 




Russia, Napoleon's campaign against, 

plague epidemic in, 6 

typhus epidemic in, 14 
Russotto, Joseph, 36 

Saipan, control of dengue-type mos- 
quito on, 119 
Salerno, 1 
San Francisco, plague epidemic in, 

7, 9 
Sawfly, control of, 169 
Serbia, typhus epidemic in, 14 
Shade trees, control of insects on, 169 
Sheep dips, 88 
Sheep, encephalitis in, 28 
Ship fever, 10 

Sicily, plague epidemic in, 5 
Silkworm, 130 
Silverfish, control of, 159 
Sleeping sickness, African, 28 
Smith, M. I., 45 
Sodium fluoride, 64 
South America, cinchona trees in, 20 
Soviet Republic, typhus epidemic in, 

Space sprays, 69, 154 
Spain, plague epidemic in, 5 
Spanish-American War, malaria dur- 
ing, 16 

yellow fever epidemic during, 23 
Spanish colonies, yellow fever in, 22 
Spittle bug 62 
Spotted fever, 10 

eastern epidemic of, 27 

Rocky Mountain, 27 

role of ticks in transmission of, 
27, 127 
Sprays, emulsion, 68, 85, 87, 154, 

household, 69, 151 

residual, 66, 154 

space, 69, 154 

wettable powder, 68, 87, 155 
Spruce budworm, 62, 134 
Squirrels as reservoirs of plague, 9 
Stable fly, 110 

control of, 155 
Standard, Commercial, CS72-38, 72 
Steuber, W., 42 
Stomach poisons, 62 
Stone, W. S., 34, 37 
Strasbourg, 30 
Streptomycin, 145 
Sugar beets, control of insects on, 

Sulfa drugs, 142, 145 
Sulfuric acid, 31, 41 
Superintendent of Documents, 72 
Surgeon General's Office, 34 
Survival of the fittest, 142 
Swiss Federal Experimental Agricul- 
tural Station, 33 
Switzerland potato crop saved by 
DDT, 33 

TabardiUo, 11 

Talc, 68, 85, 88 

Tegin, 87 

Tent caterpillars, control of, 132, 169 

Termites, 122, 123 

control of, 124, 160 
Thanite, 70 

Thiocyanates, 70, 80, 83 
Thirty Years' War, 12 
Thrips, control of, 166, 167 
Ticks, 126 

American dog, 127, l6l 

Brown dog, 127, l60 

control of, 88, 127, 160 



fowl, control of, 128, 160 

role of, in spread of spotted 

fever, 27 
winter horse, control of, 128 

Trees, control of insects on, 169 

Tsetse fly, 28 

Tuber flea beetle, control of, 168 

Turkey, typhus epidemic in, 14 

Tween, 87 

Typhoid carriers, 25 

Typhoid fever, 25 

Typhoid Mary, 25 

Typhus, 1, 10 

during Crimean "War, 13 
during World War I, 13 
during World War II, 1 
dusting with DDT for control 

of, 35 
epidemics, 1, 11-14 
rats as reservoirs of, 15 
transmission of, by lice, 1, 10, 14 
by fleas, 14 

Typhus Commission, American, 2 


United States, Dept. of Agricul- 
ture, 3, 34, 46, 64, 68, 72, 
Dept. of Commerce, 72 
encephalitis epidemic in, 28 
plague epidemic in, 7 
poliomyelitis epidemic in, 26, 

Public Health Service, 27, 114 
spotted fever epidemics in, 27 
typhus epidemics in, 14 
yellow fever epidemics in, 23 
Upholstered furniture, protection 
of, against moths, 159 


Venice, plague epidemic in, 6 

Vegetables, control of insects on, 163 
Vienna, encephalitis epidemic in, 28 
plague epidemic in, 6 


Walker-Gordon farms, 110, 117 
War, Civil, 16 

Crimean, 13 

Spanish- American, 16 

Thirty- Years', 12 

World, I, 13 

World, II, 4 
War Production Board, 42 
Wasps, control of, l6l 
Weevils, control of, 168 
Wettable powders, 155 
White pine weevil, 62, 134 
Wiesmann, R., 33 
Winter horse tick, control of, 128 
Woolens, protection of, against 

moths, 159 
World War I, typhus epidemic dur- 
ing, 13 
World War II, loss of life in, 4 

Xylene, 86, 87, 134 


Yale University, 106 
Yellow fever, 21 

during Spanish-Ameican War, 23 

epidemics, 22 

mosquitoes, 22 

control of, 24, 113 
Yellow Fever Commission, 23 
Yellow Jack, 21 
Yunan-Fu, plague epidemic in, 7 

Zeidler, Othmar, 30 
Zululand, 29